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PAULA ZAHN NOW

A Senate Office Building is Evacuated for Fear of a Nerve Gas Attack

Aired February 8, 2006 - 20:00   ET

THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.


PAULA ZAHN, CNN ANCHOR: And for folks just joining us here at top of the hour, we are going to start out tonight with tonight's breaking news out of Washington, on Capitol Hill.
The Russell Senate Office Building has been evacuated, after an alarm signaled the presence of some kind of chemical agent. A hazardous material team from the Capitol Police is now on the scene. A second test has come back negative. More testing is being done right now.

We have just heard from someone on Capitol Hill, it might take 30 to 40 minutes to process that test. Now, just a reminder that we are not talking about this going down in the Capitol Building itself, but in one of the large office buildings right next door.

And a law enforcement official tells CNN, an alarm went off in the attic of the Russell Building, signaling the presence of, potentially, a chemical agent. Eight senators and some 200 Senate staffers who were in the building have been quarantined. Many of them have been told to wait in an underground parking garage under the building.

And we understand, from an interview Wolf just did from someone who works on John McCain's staff, that there is actually some sort of tent structure set up downstairs, if, ultimately, medical attention is required.

Let's quickly turn to Ed Henry, our congressional correspondent, who has gotten this information by a number -- number of Senate sources.

What else are they telling you tonight, Ed?

ED HENRY, CNN CONGRESSIONAL CORRESPONDENT: Well, they're telling us that, basically, it was quite scary for them.

I'm talking to some people who are actually in this parking garage, adjacent to the Senate Russell Building. They heard this hazardous material alarm go off. All police personnel, all senators, staffers, ordered to leave the building right away.

The police were able to leave the buildings, but the senators and staffers were told to go to this parking garage, this so-called safe zone. What they are being told, right in that parking garage, by U.S. Capitol Police, is that, first of all, there was a first test that was found positive for some sort of a nerve agent. That's all they're being told.

A second test, though, was found to be negative. So, it's -- it's inconclusive. And, so, what we are being told is that they're -- they're basically either cleaning out or changing the filter, so that they can then conduct this third test. They're expecting the results on that in some 30 to 45 minutes.

Among the senators in there, Senator Chuck Hagel, Senator Richard Burr of North Carolina, Judd Gregg of New Hampshire. We are told John Thune of South Dakota, Chris Dodd of Connecticut. They're being held in this -- in this quarantined area, out of a fear that they could have been exposed to a nerve agent, but I stress the word could.

Nobody has -- according to an e-mail I just got that is being sent around by the U.S. Capitol Police, no one has yet shown any signs of being sick, any signs of actually being exposed to any kind of agent like that. But, under an abundance of caution, they're keeping these senators and staffers in the parking garage, until they get this third test resolved -- Paula.

ZAHN: And, Ed, I was interested in hearing, I guess just about 10 minutes ago, saying that she has in fact heard this alarm go off, once an association, I guess, with a suspicious package that had been delivered to the Capitol.

Are you ever aware of this particular alarm having been sounded?

HENRY: I have heard of this alarm. And I know it -- these types of alarms are around the Capitol, but I actually have never heard them. I mean, I do want to stress that there are false alarms of -- of various kinds, for anthrax or other things, on a fairly regular basis on Capitol Hill.

It's a fact of life post-9/11. And, fortunately, most of the time, it turns out to be nothing. But I have not personally, in all the time that I'm on the Hill, heard this hazardous materials alarm.

You see all kinds of detectors when you're walking through the corridors up there in -- in somewhat discrete places on the ceilings, that are beeping, and you can tell that they're detecting things in the air. I have never heard this particular alarm go off. I have -- one staffer, Eileen McMenamin, from Senator McCain's office, said she has heard it a few times.

And all -- all those times, it has turned out to be negative, and -- fortunately. But I have not heard it. And I have spoken to other staffers who are in this parking garage who were quite alarmed when they heard this alarm go off, because they had never heard it before -- Paula.

ZAHN: Ed, please stand by. I want to give you the opportunity to call back a couple of your sources.

And, while you're doing that, I am going to bring Pat D'Amuro into our discussion, who used to be with the FBI, is now a CNN security analyst. Pat, first of all, your reaction to this third test that's being conducted. We are told we probably won't have the results to this. The first test came back positive for what could potentially be a nerve agent, the second one negative, and now these current tests being done. What do you make of all this?

OK, unfortunately, we lost our -- our signal with Pat D'Amuro.

But it does beginning the question about the kind of testing situation that these agents might have on the ground right now, and how accurate that might potentially be.

Once again, a reminder now that we have some 200 Senate staffers sort of holed up in a -- a garage right now. They have been told they can't leave what is being called a safe zone. We know that, inside that, in addition to those staffers, are Senator Byrd (sic), Gregg, Thune, Dodd and Hagel.

Let's check in with Kelli Arena, who now has some more information from our Washington bureau.

Kelli, what are what are your sources telling you?

KELLI ARENA, CNN CORRESPONDENT: Well, Paula, my sources are cautioning, saying, look, you know, we have nothing confirmed here.

These field tests, you should know, are very sensitive. And they often give off false positives. And there are often a series of tests that need to be done, that take a little bit more time, to really figure out exactly what they're dealing with.

And while it is true that initial testing indicated that there was a positive reaction for a nerve agent, subsequent testing, of course, was inconclusive. And -- and that happens more often than -- than our viewers probably are aware.

There are so many white powder calls, as they call them here. Law enforcement officials head to the scene. And -- and, at first, it tests positive, and, then, subsequent testing turns back negative, and -- and, you know -- this does seem to be, though, more precautionary moves that are -- that have been taken, when we don't often see buildings that are entirely evacuated and people held for as long as this group of people have been held.

But I have to tell you, Paula, the law enforcement officials that I have spoken to are -- are -- are really cautioning us to -- to take a deep breath and know that nothing is conclusive at this time, and to stress that these field tests are sometimes overly sensitive.

The technology is a lot better, but it's still not where they want it to be -- Paula.

ZAHN: Can you give us a better sense, Kelli, of the kind of resources that Capitol Police have on hand, on site, when something like this happens?

ARENA: Well, I -- I can't get into sort of the technical, you know, machinery that they have.

But I do know that it -- it's a lot more sophisticated than it was pre-9/11. And you also have, not only Capitol Police, but you have the FBI's hazardous material team as well that responds from the Washington field office in this situation.

And -- and they do have usually mobile units that they can test in. And, then, what they probably will do is grab it back and take it to the lab, the FBI lab, for further testing that would be more definitive, in terms of results. But they -- they usually are able, though, within -- within, you know, an hour or two, pretty able to determine, pretty definitively, what it is that they're dealing with.

And I think that we will probably hear that within the course of your program, Paula, whether or not this is for real, but Capitol Police...

(CROSSTALK)

ZAHN: Well, what -- whatever we're looking at, Kelli, they're sufficiently concerned on Capitol Hill tonight to have evacuated these folks and to have sent 200 staffers, as well as, we are told, eight senators...

ARENA: Exactly. Right.

ZAHN: ... to a parking garage to wait this thing out.

ARENA: As I said, we haven't seen this -- right.

We haven't seen this type of reaction before, but -- but lots of cautionary, you know, advice going out. They're saying, look, you know, keep in mind, these field tests are not as accurate as we would like them to be, inconclusive at this point. It may turn out that -- that we are dealing with something positive, which, of course, then brings in a whole other layer of security that would be put in place -- Paula.

ZAHN: Kelli, we are going to let you go to continue to work your sources...

ARENA: You got it.

ZAHN: ... and figure out any new information you can share with our audience.

And joining me now on the phone is Dean Wilkening. He is with the Stanford Center For International Security. He is an expert on biological warfare.

And, sir, I -- I guess we need to point out that, so far, our -- our sources are telling us that this alarm signaled some kind of presence of a chemical agent, not a biological agent.

The distinction here?

Unfortunately, I think our line has gone down with Dean -- Dean Wilkening.

Please, understand that there is an awful lot of information we're trying to bring to -- in to you from 16, 17 different sources.

Let me take one more crack at Mr. Wilkening.

Are -- are you there, sir?

DEAN WILKENING, STANFORD CENTER FOR INTERNATIONAL SECURITY: Yes.

ZAHN: OK.

WILKENING: Can you hear me?

ZAHN: I just -- yes, I do now. Thank you for your patience here.

I just wanted to reestablish with our audience, what we are being told is that this alarm signaled the presence of some kind of chemical agent. Originally, we thought it could be a biological agent, but now we're being told a chemical agent.

The distinction between that and a biological agent?

WILKENING: Well, I should, first of all, reiterate what I gather a number of other people have told you, that the chance that this is a false alarm in the detector is probably fairly high, as I think somebody mentioned.

The more sensitive these detectors get, the more likely you will see false alarms out of such detectors. If it is a chemical agent, as you have suggested, one thing that's interesting to note is that chemical agents act very quickly on humans.

And, so, if there was a fairly high concentration of chemical agent in the office building, people would have smelled it. They would have come out of the building with stinging eyes, difficulty breathing, dilated eyes, and the sort. And, apparently, nobody's reporting symptoms from anybody down there in the garage.

ZAHN: No.

(CROSSTALK)

ZAHN: In fact, the last report we got described people being as quite relaxed about all this...

WILKENING: Right.

ZAHN: ... and not terribly worried.

WILKENING: Probably a bit bored with the whole thing.

Yes. Well, you remember the incident in the Tokyo subway in 1995, when Aum Shinrikyo released sarin gas, which is a nerve agent. And people were fleeing the subway with tearing eyes. They were covering their faces. They were choking, difficult breathing. Some people collapsed. That's the kind of event you witness when a nerve agent is released in modestly high concentration.

And even the Tokyo subway incident was relatively low concentration, compared to a -- a sophisticated attack. So, given that nobody is showing those symptoms, and given that the sensor indicates that it's chemical and not biological, my guess is -- and I hesitate to go too far out on a limb here -- my guess is that this is probably a false alarm.

ZAHN: Well, I hope you're right.

And, Mr. Wilkening, just stay with me for one second, because I want to go through the information we have had confirmed from a couple of Senate sources.

One is that the first test that was done came up positive, the second test, negative.

(CROSSTALK)

ZAHN: The third test is in the process of being done right now. We're told maybe 8:30 would be the earliest we would get the results back from that.

Can you describe to us what you think is happening on site? We know that we have the Capitol Police working now in conjunction with the FBI hazardous material team. What kind of equipment is required to do this kind of testing?

WILKENING: Oh, there are a number of different field sensors that people can bring in to detect a chem -- the presence of chemical agents. The U.S. military has some.

They may be on loan to various people in the Washington area. I don't know if the Washington, D.C., police has this equipment or not, but I'm sure that the hazardous material teams that have been called in to this event have a range of different sensors. Now, they -- they tend not to be as sensitive as laboratory tests.

And, so, it wouldn't be surprising that some of them come up false. Maybe another one will come up positive. But suffice it to say, there are a range of detectors...

ZAHN: All right.

WILKENING: ... that...

(CROSSTALK)

WILKENING: ... be brought into the -- the scene there, and to double-check to see whether there are high concentrations of a nerve agent.

ZAHN: And -- and, when you talk about the range of -- of testing available, what are we to understand about the reliability of any of these tests, then, on site? You had made the point earlier, with the more sensitive these -- these detectors have become, probably, the greater the chances of a false positive.

WILKENING: Yes.

Well, let's put it -- let's turn the question around a bit. If there's a high concentration of chemical agent, nerve agent, in the building, in the air in the building, then, most of these detectors are going to detect it fairly reliably.

So, they will be finding positive indications very quickly. If the concentration is very low, then, that's when the sensors -- when you get close to the sensor threshold, then, sometimes, they turn up positive, sometimes negative, and the tests become much less reliable.

And, so, the fact that they are going in with various detectors and sensors and are not coming up with strong positive signals indicates that, if there is any chemical agent there, it's probably in fairly low concentration. And, so, one could infer from that, that it's -- may not be a chemical agent at all, or, if it is, it doesn't -- well, who knows...

ZAHN: Right.

WILKENING: ... if it's a deliberate attempt or not. But if it was a deliberate attempt, it sure didn't go off very well, because a deliberate release of nerve agent in a building would send off very loud alarms, and you would be able to detect it quite readily with all kinds of different sensors you bring into the facility.

ZAHN: And -- and, once again, Dean, I want you to -- to stay with me, as I walk through some of this information we have just learned in the last nine minutes.

We just had Kelli Arena, who has reported from -- through her Homeland Security sources for everybody to take a deep breath here and sort of hold our breath until these tests are done. They're urging extreme caution in jumping to any conclusions about what we're talking about.

And, yet, when you hear that you now have eight senators, as well as 200 Senate staffers, who are holed up in the building parking lot, more or less -- maybe quarantined is too strong of a word, but definitely holed up -- it does make you wonder about this alarm that, in fact, went off in the attic of the Russell Building.

WILKENING: Right.

ZAHN: Let me ask you this.

If it turns out that there is -- we have one test showing positive, the second one, negative, third one now being conducted -- that -- that there is the presence of some sort of nerve agent in this building, can you describe us to how this would even get into the building, how it would be carried, how it would be transferred?

WILKENING: That's hard to speculate.

If it's a deliberate attempt -- well, first of all, some of the chemicals of the effluence inside of buildings might fool sensors, depending on the kind of building material used in the building.

But if it was a deliberate attempt, presumably, people, they -- they might carry a small vial of nerve -- nerve agent into the building, although that's pretty hard to do undetected, although I suppose it's possible. I don't know how they got in the attic, since that's where the sensor went off.

That would not be the best place, necessarily, to release nerve agent, unless there's a big air intake there. Most of the scenarios people worry about are where a terrorist comes up to some air intake and dumps it right into the air intake, and then the -- the heating ventilation system sucks up the agent and spreads it all over the building.

But, again, those scenarios, you would have a very -- a dramatically different situation unfolding than what has been described so far.

ZAHN: Sure, because I think...

WILKENING: You would have...

ZAHN: ... one of the things you were talking about that you would have immediately seen, had there been a high concentration of a nerve agent in the air, that -- that people's eyes would have been watering, and they would have had a pretty strong physical response...

WILKENING: Oh, they would describe it..

ZAHN: ... to it, which is not...

WILKENING: They would be...

(CROSSTALK)

WILKENING: Yes.

ZAHN: ... what we have heard described.

WILKENING: Right.

ZAHN: Dean...

(CROSSTALK)

WILKENING: They would be describing a foul smell. Often, these things are very acrid. Yes, their eyes -- they would have blurry vision, choking, chest problems, all kinds of very distinct, very sudden onset symptoms, if you will.

ZAHN: OK.

And, Dean, again, please stay with us, as we continue to try to elicit information from a whole bunch of sources out there.

Once again, all we can confirm at this hour is that law enforcement is telling us that an alarm went off in the Russell Senate Office Building, signaling the presence of some sort of chemical agent. A first test came back positive. A second test came back negative. A third test now being done.

Dean Wilkening, who is an expert in all this, just explaining to us, it would not be unexpected, perhaps, if this was a false alarm. For example, if you had a very, very high concentration of this stuff, clearly, it would have set off the alarm.

But where this gets a little more murky is if you were to have low concentrations of -- of these things. And you have got various kind of, apparently, detection methods being -- right now to assess all of this.

And, as soon as we can get a confirmation on this third test, we will bring the results to you.

But, in the meantime, we are going go to some of the other day's headlines.

And, then, when we come back here, we are going to be talking with someone who is actually holed up in that parking garage of the Russell Senate Office Building, along with eight senators.

Erica, before I go to you, I can confirm right now that we know, in that garage are Senators Byrd (sic), Gregg, Thune, Dodd and Hagel, and as well as 200 Senate staffers.

So, we will go back there in a moment.

But, actually, let's go to Susan Hendricks, who joins us now with some of the other top stories at this hour.

SUSAN HENDRICKS, HEADLINE NEWS CORRESPONDENT: Hi, Paula. Thanks so much. We know it's a busy night in Washington.

We start in Los Angeles, though. The lockdown continues tonight at an L.A. prison, after continued racial brawls by inmates. Fighting last weekend at the Pitchess Detention Center killed one inmate and wounded scores of others. At least 19 may have been injured today.

The FBI now says an American charged with being part of a terrorist cell also tunneled out of the prison in Yemen last week. Jaber Elbaneh was connected to a terror cell busted in Lackawanna, New York. A suspect in the bombing of the USS Cole also escaped.

Oops. McDonald's says it's french fries contain one-third more trans fat than previously thought. Trans fat is believed to be a factor in clogged arteries. McDonald's is in the process of updating its nutrition information.

And aviator Steve Fossett took off from the Kennedy Space Center this morning in his Global Flyer, on a quest to set a non-stop flight record around the world and across the Atlantic twice.

And those are the headlines -- Paula, back to you.

ZAHN: All right, Susan -- a lot to figure out here tonight about what is going down on Capitol Hill this afternoon -- or this -- this evening.

Once again, the Senate -- Russell Senate Office Building now essentially been evacuated, after an alarm went off in the attic, signaling the presence of a chemical agent. You have got eight senators, some 200 Senate staffers, now, more or less, holed up in this parking lot, until they're told that it is safe to go outside.

Joining us right now is Kelli Arena, who has some late-breaking information from her sources at Homeland Security.

Kelli, what else have you learned?

ARENA: Well, Paula, some law enforcement officials that we spoke to said that, just now, they -- they have been checking the people that are there, that are holed up in that garage. And, still, no one is exhibiting any signs of being sick.

No one is complaining of, you know, chest pains or -- or respiratory problems at all. So, that's good news.

My producer, Carol Cratty, just got off the phone with Capitol Hill Police Chief Terrance Gainer, who is on the scene, says that testing remains inconclusive. They are still waiting to find out exactly what they're dealing with, that -- that there is no signal for anyone to go back into that building yet.

They're going keep people holed up there for some time more, until they get more definitive results -- so pretty much status quo. Those people will not be moving any time soon. We had heard earlier that -- that they might be able to move them in the next 20 minutes or so. So, far, no-go signal from there -- Paula.

ZAHN: Kelli, you made a very interesting point earlier about how sensitive these field tests are. And we just had an expert on from Stanford about four minutes ago who was talking about these tests being very reliable, when you would have a high concentration of the chemical agent, but somewhat less reliable with lower concentrations, and that's when you might get a false positive sparked.

ARENA: I was also told -- one of the -- one of the law enforcement officials that I spoke to on the phone told me that they actually had a -- a similar situation in another office building, and it was because of the cleaning fluid, the chemicals within the cleaning fluid that was used in that building. That triggered an alarm.

So, they have seen false positives like this. Again, Paula, as you pointed out earlier, they don't usually react in this way. I mean, this is -- this is unusual, in terms of the -- the cautionary, you know, reaction, but it's not like we haven't heard about these alarms going off before. So...

ZAHN: Sure.

But I do think we need to point out -- I guess we can come to this -- this quick conclusion so far -- if your sources are telling you that the folks now holed up in this parking lot have exhibited no physical symptoms of having been exposed to a chemical agent, our expert was just saying, had it been a high concentration, you would have people, you know, coughing...

ARENA: Right. Right.

ZAHN: ... coming out of there with blurry vision. A very foul smell would have permeated the place, none of which has been reported so far.

ARENA: That's right.

ZAHN: Correct?

ARENA: That's right.

ZAHN: All right.

Kelli, you stand by. And keep on working the phones for us.

And let's turn to Jeanne Meserve, who also has excellent contacts at Homeland Security Department, to tell us what she has learned.

Jeanne, what are...

JEANNE MESERVE, CNN HOMELAND SECURITY CORRESPONDENT: Oh, Paula...

ZAHN: What are your contacts telling you they make of this?

MESERVE: Paula, it seems to be a bit of a confusing situation.

I just spoke to one official who is in very close contact with the scene. And he tells me that, yes, a sensor did go off, but there have not been follow-up tests as yet, that they're preparing to send a team in. It would be a combination of D.C., fire and Capitol police.

They're suiting them up. They will go in. And he says that the detection devices they have for a chemical agent -- and if we're talking about a nerve agent here, that is a chemical -- that they would be able to determine in pretty quick order whether or not they're dealing with the real thing or not, and that, as other people have said, it's a very positive sign that, thus far, nobody has been symptomatic at this point in time.

So, this -- this is a question, whether we're dealing with a chemical agent or a biological agent. It is the biological field tests that are unreliable, that often come back with false positives. Testing for chemical weapons is a lot more precise. Let me tell you a different line, this gathered from Steve Turnham, one of our producers. He talked to a staffer who is amongst those in the garage. This person told Steve that, initially, the enunciator system in the Capitol, in the Russell Office Building, broadcast that alarms in the attic had gone off. The enunciator system is sort of their mini-broadcast thing that sends alerts through the building.

It told them that a sensor had gone off in the attic. About 30 minutes later, they were told to evacuate. They were not allowed to go outside of the building. They were sent from the building right down in to that parking garage. This person says that they were told by the Capitol Police -- and, again, confusing info here -- the Capitol Police told them there had been a second test; the second test was positive for a biological agent. And, then, there was a third test; they are going to be checking the filter on the sensor.

So, what are we dealing with here? Is it a nerve agent? Is it a biological agent? We just have very conflicting reports at this point in time.

ZAHN: Exactly, Jeanne, because we actually reported the exact opposite of that, which is understand -- understandable, as everybody's trying to make sense of this.

We had the first test coming back positive for a chemical agent, the second negative, the third being done now. And you said -- your sources said the second one came back positive for a biological agent.

MESERVE: Right.

But, understand, this is a Senate staffer who may not be particularly well versed in the intricacies of testing and may have misunderstood something that was told to him from the Capitol Police. But this is one of the people involved in this incident. He's one of those people who has been put down in the garage. This is what he says they're hearing.

He also says that there are fewer senators there than -- than we believe. He said Senators Gregg, Hagel, Thune and Burr are the four senators who are down in that garage.

ZAHN: Repeat that one more time, Senators Hagel, Thune, Byrd.

MESERVE: Burr -- B-U-R-R.

ZAHN: Burr. Oh, Burr.

MESERVE: Not Byrd.

ZAHN: OK.

MESERVE: And Gregg.

ZAHN: OK. We were told two more than that. So, we will continue to work on that. Jeanne, clear up one more piece of information that seems contradictory. We were originally told that the FBI hazardous material team was either on the scene or en route, in addition to Capitol Police. And you are now saying that D.C. Fire and Capitol Police are getting suit up -- suited up to go in.

MESERVE: You're right.

This is a very confusing jurisdictional picture here in the District of Columbia. And Capitol Police is quite proprietary. But, in an instance like this, they would certainly call on the resources of the FBI and of D.C. Fire.

I do know that a decontamination tent has already gone up in the area, in preparation for teams and what they might be confronting when they go in, or if they have gone in -- as I say, a very muddy picture right now.

ZAHN: And, Jeanne, can you also help us with the picture that we see endlessly being re-looped on screen? From -- from where I'm sitting, I can't make out this intersection. Can -- can you make it out?

MESERVE: You know, I wish I could. But the monitor I'm looking at is small enough that I'm not able quite to make out exactly what that is.

Obviously, it's the streets outside of the Russell Office Building. But I can't be any more precise with you than that. I'm sorry, Paula.

ZAHN: Jeanne Meserve, thank you so much for the update.

MESERVE: You bet.

ZAHN: We will continue to come back to you.

And we are told that a news conference is expected, potentially, to get under way by Capitol Police in the next four or five minutes. When that happens, we will bring it to you live.

In the meantime, we are going to get some really good information now from Eileen McMenamin. She's a spokeswoman for Senator John McCain of Arizona. She also happens to be one of the evacuees.

Eileen, describe to us what happened from the first moment that alarm went off.

MCMENAMIN: Sure, Paula.

It's a little bit different than some of the reports that I have -- I have heard coming in on the air. And I -- I just wanted to make clear that, when the initial alarm sounded, and they said to immediately evacuate the building, no one stuck around for half-an- hour. We grabbed our coats. We grabbed our bags. We didn't log off of our computers. We were running down the hall to evacuate. They said everyone, including senators, staffers, U.S. Capitol Police, need to leave the building immediately. So, we took off running.

They -- they would not let us go outside. They separated us all into this west garage here, where we are now. They have got air monitor systems set up. They're testing the air continuously, to make sure that we are in a safe zone.

There is a tent set up here in the garage, I guess in case there is some sort of a positive result. And it looks like they would be ready to -- to offer some sort of treatment. I'm not quite sure what that would be.

Some of the officials here at the scene tell me that they are testing filters now where some of the -- where the first hit supposedly happened in the attic of the Russell Senate Office Building.

One of the medical workers down here did tell me that it's possible that, if there are -- if people are contaminated, they may not show symptoms for up to three days. And he says -- but -- but they are -- they're doing continuous tests. And if a test does come back positive, they obviously wouldn't wait for anyone to become symptomatic.

They would begin (INAUDIBLE) antibiotics immediately, if there was a -- a positive result from any of the tests.

ZAHN: And, of course, Eileen, you haven't been able to listen to all of our coverage tonight.

But because there is so much that's not clear from this testing tonight, there's a tremendous amount of confusion about what kind of reaction those of you that potentially could have been exposed would have.

We just had an expert on a while ago that said, had there been a strong concentration of the chemical agent, you certainly would have seen right now, by now, a physical manifestation, in either a -- a foul smell, blurry vision, watery eyes, a lot of coughing. You have seen no one exhibit any signs of that, correct?

MCMENAMIN: Right. That's absolutely right.

People are here. They're sort of antsy to get home to their families, but no one seems to be exhibiting any signs like you mentioned, you know, no like watery eyes, and, you know, really violent reactions or anything like that.

Like I said, they do have this medical tent set up here, in case anyone were to have any symptoms. But no one seems to be going over there at this point.

ZAHN: And can you confirm -- we know that 200 Senate staffers are very important people, but we have also had varying accounts on the senators, though, that are holed up down there in the parking garage with you.

Confirm who you have seen.

MCMENAMIN: Sure. I have seen myself Senator Hagel, Senator Thune, Senator Burr from North Carolina. Those are the only ones that I have actually seen. There may be others here, but there are quite a number of people down here. And it's a somewhat limited space.

ZAHN: Eileen, I don't know if you are close--you know what, I am going to come back to you. But we would love to talk to one of those senators if you would be kind enough in a couple of minutes to hand the phone to one of them.

I am going to break away so we can listen to Capitol police that are now stopping--well, apparently it hasn't started.

All right. Eileen, in the meantime, just once again describe the mood of folks down there. There's not a whole lot of fear. There's just more sense of anxiousness about getting home?

MCMENAMIN: Yes, I think so. I mean, the Capitol Police have been pretty good about briefing us. We have gotten briefed a couple of times about the situation and what to expect. We should have another briefing here within the hour.

They did in the last briefing, Paula, use the words nerve agent. So that got some people a little bit nervous down here. But they said that, you know, obviously the first test was positive. The second test was negative, but now they are conducting this third test. And we are supposed to be hearing within the hour what the result of that is.

ZAHN: Did any of these officials happen to mention that some of these detectors now are so sensitive that there is a chance that there could have been a false positive from the first test that came out positive?

MCMENAMIN: Sure, sure. That's absolutely a possibility. They said that the first test being positive could have been a result of something as minor as fertilizer. So, you know, I think that's why they are doing some continued testing. And they really don't want anyone leaving the facility here until they have, you know, absolute confirmation that something has occurred.

I think that they may--there was some mention about maybe taking down the names of people that are here in case anyone is affected or develops symptoms later on.

ZAHN: All right, Eileen. Let's break away now for the news conference from Capitol Police.

SGT. KIMBERLY SCHNEIDER, U.S. CAPITOL POLICE SPOKESWOMAN: Ready to go. Good evening this is Sergeant Kimberly Schneider, public spokesperson for the United States Capitol Police. At approximately 6:30 this evening we received an alarm at the Capitol Police for a nerve agent in the attic of the Russell Building. This is on the Senate side of the Capitol.

At this time we have received negative results on this testing. We are taking samples to our testing facility. I will take any questions that you may have at this time.

QUESTION: Where is your testing facility?

SCHNEIDER: That's in a location in Washington, D.C.

QUESTION: Are people still in the building or are they being allowed to leave?

SCHNEIDER: People have actually been evacuated. We have an area in the west legislative garage of the Russell Building, which is about two blocks from here. And people have been directed to that area approximately 200 plus individuals at this time.

QUESTION: Are they being just held there?

SCHNEIDER: They are being briefed on the situation, and they are also being cared for.

QUESTION: One of those individuals being held say that symptoms would not show for two to three days depending if it is prevalent. What's the course of action after that?

SCHNEIDER: Well, I will tell you that our tests initially indicated a nerve agent. Subsequent tests have indicated that it is not a nerve agent. At this time nobody has indicated that there are any symptoms present. Symptoms normally would indicate would be a runny nose or something of that nature. That would indicate a presence of a nerve agent. And nobody has reported that thus far.

QUESTION: How many senators were in the building at the time?

SCHNEIDER: I can tell you that roughly a dozen or so senators are now in the west legislative garage being briefed.

QUESTION: Are staffers being told to come back?

SCHNEIDER: Staffers have been evacuated. Anyone who is in the building has been evacuated from the building at this time. Noone has actually been told to return at this time yet.

Right now this is affecting the Russell Building.

QUESTION: Sergeant were there any communications, any letters, notes, threatening phone calls?

SCHNEIDER: That information is not available right now. To my knowledge, I have not received that information in regards to this incident.

QUESTION: What was the nature of the substance? Was it a powder? Was it a liquid?

SCHNEIDER: It is actually--what the initial test indicated was that it was a nerve agent so that is what the suspicious substance was.

QUESTION: But you don't know whether it was powder, liquid?

SCHNEIDER: I don't have that information.

QUESTION: Where exactly in the attic was it found? Is there a mail room there?

SCHNEIDER: In the attic there are several storage facilities, small storage spaces in the Russell attic. I'm not sure what the location was in the Russell attic. It is rather a large area. It actually takes up the entire floor of the Russell Building so it is a rather large area.

QUESTION: Can you tell us what the nerve agent was that the alarm triggered?

SCHNEIDER: I don't have that information for you. I intend to give another briefing later just so that you all know so we can keep up to date on the information. And we'll get that for you.

QUESTION: Was it an actual package or substance or was it just something that triggered the alarm?

SCHNEIDER: Something in the air would be a more accurate description rather than a package. The alarms that we got was for a nerve agent. That would not a be package. That would be something that would be in the air. That was the initial test.

Many of the tents that you see are decon tents, decontamination tents. When people come out of the building they have to be in the proper protective gear in order to enter the building under these circumstances, and one they come out they do have to be decontaminated. And that is just routine procedure.

QUESTION: What's the procedure as to who gets to leave the building and who gets to go to the garage?

SCHNEIDER: Anybody who was evacuated from the building was moved to the garage. That was our procedure this evening.

QUESTION: Have they been released?

SCHNEIDER: They are still in the garage to my knowledge.

QUESTION: Do you have a timeline on when you expect the further tests and how long these folks will be held in the garage?

SCHNEIDER: Well, our experts are determining what the nerve agent right now. I don't have a timeline as far as when people will be released from the garage. I know we are keeping everyone up to date. We want to keep everyone safe. We want to keep everyone briefed and make sure everyone is certainly in the loop with our security procedures. And that's why we will keep everyone until we don't have a need to keep them anymore.

QUESTION: Did they go to the garage? Was it underground or how did they get from Russell to the garage?

SCHNEIDER: That information is unknown. I can tell you there are two ways to get there. You can get there from inside the building. You can also get there from outside the building.

QUESTION: Whatever the substances, what are the chances that it would have gotten into air vents beyond the attic?

SCHNEIDER: We do take precautions to make sure that--we have learned from our previous experiences up here on the Hill, we do take precautions to make sure that our congressional community is protected, if we do have any indications of a nerve agent. I can assure you of that.

QUESTION: So it wouldn't have gotten beyond the attic?

SCHNEIDER: I can assure you that we have security procedures in place and we are extremely concerned about keeping our congressional community safe. And we have several security procedures in place which we do enact.

ZAHN: You have been listening to Kimberly Schneider of the U.S. Capitol Police giving the public its first briefing on what the heck is going on Capitol Hill tonight. This is the best we can cobble together the story at this hour.

The Russell Senate Office Building was evacuated earlier this evening when an alarm went off indicating--and it was in the attic, which Kimberly was just describing as an entire floor of the Russell Office Building. An alarm going off in that attic signalling the presence of a chemical nerve agent.

This is where the story becomes a little less clear. Initial tests came back positive. The second test came back negative. Now, contrary to what we were originally told, the tests are not being done now on site. According to her, the samples are now being taken to a testing facility in Washington, D.C. No indication on when the results of those tests will come back.

Kimberly Schneider saying that at least a dozen senators are held up in the west legislative garage along with 200 staffers. We have spoken with some folks underground not that this is critically important at this hour.

They have been able only to confirm the presence of three senators down there at this hour, Senators Hagel, Senator Thune and Senator Burr of North Carolina.

Let's quickly go back to Kelly Arena who has been working her homeland security sources for the very latest from her end--Kelly.

ARENA: Well, Paula, everything that you heard in this press conference is pretty consistent with what my sources are saying.

One that of course the testing so far is inconclusive, that it will be brought to a lab for more definitive results, that no one that is in that garage has exhibited any symptoms of being exposed to any sort of a nerve agent. And we don't have a specific timeline for when they will have a definitive answer or when that building will be given the all clear.

And there are no other incidents right now that are similar in nature that are being reported in the Washington area either, Paula.

ZAHN: Now, the one question we didn't get a clear answer to was whether there was any threatening phone call made, any threatening letters made. She wasn't able to share that information with us obviously. What have your sources said about that?

ARENA: My sources have said no that there was nothing accompanying this that would lead them to believe that there was anything, you know, threatening going on. They have not heard of any communication whatsoever.

ZAHN: Kelly, please stand by.

I am going to quickly turn my attention to Ed Henry now, our congressional correspondent, who was the first to break the news of what is going down tonight on Capitol Hill.

What else have you learned, Ed?

HENRY: Paula, one of the sources who first tipped me off to the story who was inside the parking garage just emailed me to say that the police have just announced to the people...

HENRY: Paula, one of the sources who first tipped me off to the story who is inside the apartment garage just e-mailed me to say that the police have just announced to the people in the garage, the senators and the staffers, it's going to take a lot longer than they originally anticipated.

We were reporting a short time ago it might be a half hour when they'd have that conclusive test. They are now being told by the police at least another hour. They are being told there are two tubes of material that need to be tested. They're collecting names of people so they have it all catalogued, but I can tell you that the mood of the people I'm talking to inside the garage is quite good.

One staffer for Senator Jeff Sessions of Alabama just called me and said Senator Sessions is one of the people in the room. He is in black tie, like I am, because he was headed to the same press dinner that I'm supposed to be at right now, but Senator Sessions is very calm. He's telling his staff he's fine. As we've been reporting, no symptoms.

In fact another staffer e-mailing from the room that they want somebody to send some pizza over. So you can imagine people are almost -- I don't want to say humorous about it, this is a very serious situation, but they're trying to take it in stride, they're hoping for the best, that this is just a false alarm. And quite frankly, they're hungry right now and they want to go home, Paula.

ZAHN: A slightly lighter point of view than what Eileen McMenamin, who was on the staff of Senator McCain described, when a couple of people, she said, you could hear were profoundly affected when they heard there was the potential perhaps of a nerve agent having been in the building.

So, Ed, walk us through, the best as you can figure this out because our sources have told us a bunch of different things tonight about these tests. Is it your understanding that from your Senate sources that the first test came back positive for the presence of a nerve agent, the second one negative and now the third test, of course, being done off-site at a testing facility in D.C.?

HENRY: That's the best information we've had from multiple sources, not just one person here or there. Multiple sources, some of them inside that room, others coming second-hand from senators and staffers calling back to their colleagues and telling them the information is that there was a one test that was positive.

A second test that was negative and now this third test is being done again, two tubes of material being tested. The police just saying the last few minutes.

There may some question though, was that first test, so-called test, the detector that went off? That's unclear to me. Was it an actual test of the material or are they saying that the quote on quote, "positive test" was that first detector sounding an alarm saying there's something here and then a second more specific test saying negative. That's something we're not sure of now and I don't think the police really made that clear, Paula.

ZAHN: Ed, stay with me for a second because we had a chemical scientist who specializes in these materials say to us that it is his belief that these tests are highly reliable when you have high concentrations of a nerve agent in the air, less reliable when you'd have a lower concentration and that would be when you would get a false positive, perhaps a false alarm.

HENRY: Yes. And you know, the people, initially, who were there in the garage, they're obviously not experts on this issue. Some of them were initially telling us they were being told it was biological. Then others saying nerve or chemical and consistently the vast majority of people in there have said nerve or chemical and you heard that from the police, that it was not biological nerve agent.

In terms of the details of it, this is something they don't deal with every day. The people in the room are -- you know, as I said, while they're trying to take it in stride, as you noted, some of the ones we've spoken to are quite concerned just because they've never seen a situation go to quite this level. It is fairly routine as Kelli Arena has been reporting, that we get false alarms and they move on. But usually we get that false alarm announcement sometimes within minutes just because it's going longer didn't mean it's ominous, but it's certainly concerning to the people there. They want to know that it's a false alarm as soon as possible.

ZAHN: And the other concerning thing, Ed, of course, as we heard. One of those witnesses down underground describe a medical tent having been erected and she said that she was assuming that was being set up potentially if someone need to be treated down the road.

But once again, the good news is not only from our guest that said, but Kimberly Schneider of the U.S. Capitol Police, it does not appear that any of the people who were evacuated are showing any signs of a physical reaction to what potentially could have been an agent. No watery eyes, no coughing, no blurry vision, none of those obvious signs that would normally exhibit themselves if there was a high concentration of a nerve agent.

HENRY: That's right, and I think the medical tent being set up, obviously you can safely infer that it's an abundance of caution. It doesn't mean that they're expecting a lot of people to take ill, but they want to be prepared.

For example, when I was driving over here to the bureau from Capitol Hill to report this story, I saw fire engines coming from every direction, more than I've ever seen on the Hill at one time. And I think that was also an abundance of caution, obviously. There was an all-call to as many fire engines that they could get from the nearby scene from various jurisdictions here within the city to aid the U.S. Capitol Police.

Again, that doesn't mean that it's going to be ominous. It just means that they're pouring as much resources as they possibly can in terms of medical tents, in terms of fire engines and police personnel to just make sure that they're on top of the situation.

ZAHN: Ed, we're going to break away to give you a chance to read the all e-mails, I'm sure about a hundred of them have amassed since we've been speaking over the last couple of minutes because he has great sources down there under the ground. Let's quickly turn to Jeanne Meserve, who's also been working this every way she knows how. Jeanne, what else have you learned?

JEANNE MESERVE, CNN HOMELAND SECURITY CORRESPONDENT: Paula, I just wanted to say that this isn't the routine thing. Since Anthrax, there have been numerous reports of various biological agents. In fact, I heard a D.C. fire official say the other day, they get on average three a day in the city of Washington and if there's been an incident somewhere else it can go up to more than 80 calls a day on suspicious white powder where people think it's a biological agent.

This was an alarm for a nerve agent, a chemical weapon. That is very different than a biological agent, far different impact. So this response that you're seeing is not what you would see on the average call, on the average day, the setting up of decontamination tents, the preparation for possible medical treatment, the decision to take these people and keep them in isolation until they know exactly what they're dealing with. Some of them, yes, you'd see with a biological agent, but some of this response is a little bit different because this alarmed on the nerve agent rather than something that was biological.

ZAHN: And once again, clarify something for us because we've had a couple of contradictory reports on this. Do we -- we have Reuters reporting that nine people in hazardous material suits have actually gone into the building. Kimberly Schneider of the U.S. Capitol Police made it sound like folks were still getting suited up for the U.S. Capitol Police to go in. What's your understanding?

MESERVE: I would have to defer to the U.S. Capitol Police on that one. They're the people who are on scene. They're the people who are in charge of this incident. I think they probably have the very best handle on what's happening up there.

ZAHN: All right, Jeanne, you please stand by, continue to work your sources, we're going to quickly turn to Dr. Sanjay Gupta, who understands a lot of the details of what goes on with this testing and what's going on at this hour.

So Sanjay, we now have had it confirmed by U.S. Capitol Police that samples now have been taken to an outside testing site to be done because of these contradictory results. The first test positive coming back for the presence of a nerve agent, the second test coming back negative. The third test now either being conclusive or still being processed depending on who you talk to. What do you make of all that?

DR. SANJAY GUPTA, CNN SENIOR MEDICAL CORRESPONDENT: Yes, you know, it's a little bit hard to get a sense of everything. Obviously, a little bit of confusion there, not surprisingly. The first test you almost got a sense listening to that press conference, just like you did.

The first test was actually the sensor itself going off and I think that sort of sounds like what they're considering the first test, than when they actually went in there and tested for an agent. It sounded like that test was negative.

Now a third test being done. It's hard to figure out exactly, Paula. A couple of things that sprung to my mind is I don't know if the terms are sort of being thrown around a little bit loosely in terms of nerve agent.

I did hear the press on Capitol Hill, the spokesperson say that, versus a chemical agent. A nerve agent could be a type of chemical agent. Then you heard Eileen from Senator McCain's office saying they were told it could be up to a couple of days before they would exhibit symptoms and that certainly doesn't sound like a nerve agent when someone is telling you that it could take a couple of days.

ZAHN: No, because our other expert was saying that you would have immediate symptoms, particularly if there was a high concentration of it in the air.

GUPTA: That's right.

ZAHN: Your eyes would be burning, you'd be watering, you'd be coughing. What else would be obvious?

GUPTA: You might be drooling, you might develop some chest tightness. You'd feel very uncomfortable for sure. Your pupils might start to constrict, you'd have trouble seeing. All that could be happening. It would happen pretty quickly.

There is one type of nerve agent called V.X. nerve agent, in which the symptoms could take a little bit longer to develop, but absolutely Paula, for the most part with nerve agents you'd know pretty quickly.

So the one thing from your previous interview, I was just listening where they were told by somebody that it would be a couple, three days before they might develop symptoms -- that throws it a little bit into question, as to exactly what they're thinking.

When you say a couple, three days, that puts it back more into the realm of biological agents. I just heard Jeanne Meserve say that's not likely for sure. But when you two-to-three days, you do think about things. Like we've talked so much about in the past with Anthrax. Things like botulism as well. Those types of things can take a little bit longer to develop symptoms. So it just seems like there's a little bit of lack of medical information. Again, not surprisingly, coming out right now.

ZAHN: Let's also put in perspective the fact that we've had the Capitol Police confirming that decontamination tests have been set up outside the Russell Office Building and of course anybody that enters the building now that it has been evacuate has to go in suited up and of course go through the decontamination process what they come out.

They made it sound like that was being done simply as a precautionary measure and part of this, I suppose you would call it, investigation, that they're a part of.

GUPTA: Yes, you know, and Paula, you talk about the different types of agents here. You know, you talk about the nerve agents, obviously. There's also blister agents like mustard gas, which this doesn't sound like it, biological agents. All of those would probably require some sort of decontamination depending on your index of suspicion.

With the nerve agents in particular, there's medications that can be given specifically Atropine is a medication that they can be given very quickly. Sometimes it's given even if you can't confirm the presence of nerve agents just because it's not going have any long lasting detrimental effect and it could possibly help. So that's a medication that's sometimes given.

Sometimes as part of the whole medical care you have actually ambulances set up. You can hear them in the background I think there. Also possible breathing tubes in case someone does develop any difficulties. But, again, this just doesn't all--it is not all fitting together, Paula. The nerve agent, again, to say the sensors went off, nobody had any symptoms. Maybe it was just a very small concentration. Maybe it was a false positive or maybe it is something else altogether, Paula.

ZAHN: And I wish we could get contacts to that rapid response truck. It looks like it's leaving the scene, but we do know that Capitol Police, of course, have their resources on the ground. The FBI, we are told, is moving. It has its hazardous materials people into this area as well.

Once again, you've got 200 Senate staffers now underground in what they call the west legislative parking lot along with what the Capitol police say are a dozen senators. We've talked with folks underground who have only been able to identify five senators. So there's a lot of information coming at us in different forms, often contradictory.

Let's turn to Mike Brooks, who is a security analyst, who can give us some insight as to what we're looking at on screen and potentially what could be happening inside the Russell Office Building right now--Mike.

MIKE BROOKS, CNN CORRESPONDENT: Hi, Paula.

That vehicle you were just talking about that just went down the street. That is a support vehicle of the D.C. Fire Department Hazardous Materials Unit, but the U.S. Capitol Police has their hazardous material response team that is suited up.

And we heard that there were nine people in suits going in there to take samples. That is a normal procedure that they would take if they went in to take samples off of the filters, put them in the two tubes and them send them to a lab.

Now, there are a number of labs in the Washington, D.C. area that can do tests for chemical, biological, radiological, nuclear. And that's where they're sending them now. It will probably take at least an hour, possibly more to make sure that there is no hazardous material within that particular tube.

But the U.S. Capitol Police, the D.C. Fire Department along with the FBI's National Capitol Response Unit, which is also capable of having equipment to go into assist U.S. Capitol Police. They're some of the best in the country, and they're in good hands there on Capitol Hill.

ZAHN: And let's try to make sense of some of what else Kimberly Schneider said in the U.S. Capitol Police briefing we just had. When someone asked her what this material might have looked like had it been a nerve agent and she really didn't go to any details.

What would it look like?

BROOKS: The nerve agent could be something that would be basically -- have some kind of odor to it, but basically if you look back and you look at the sarin attacks back in Japan a number of years ago back in 1995, those were nerve agents that were used in that particular case. People were instantly overcome by the sarin.

If this had happened, if there was an actual nerve agent in the attic of the Russell Senate Office Building there would be immediate, immediate, you know, runny nose, tightness of the chest, other symptoms that people would be indicating.

And now we hear that the 200-plus staffers and 12 senators that were evacuated to the garage, no one has indicated any symptoms whatsoever. That's a good thing.

ZAHN: But Mike, this is where it gets a little bit confusing because one of our other guests said that underground when they were briefed they were warned even though they were being told it was a nerve agent that it could be three days before they exhibited any symptoms of having been exposed to an agent, which got Dr. Sanjay Gupta to thinking that now this picture is even more confusing than we thought.

BROOKS: Well, it is. And I agree with Sanjay, but what they also may do, you know, since the first test was positive, the second one was negative we're waiting for the final test to come back from a lab. They could just also be preparing these people who are in the garage for a possible nerve agent, a chemical agent or a biological agent.

Now, you know, it's 24, 72 hours down the road, it could be something such as, you know, that we've seen before and up on Capitol Hill. It could be anthrax. And they could be just preparing these people that, you know, if in fact it does come back with a positive for one of these chemicals that this is what they may be looking at down the road.

ZAHN: All right.

BROOKS: But my sources have told me, Paula, that the initial indications was a nerve agent in the attic there from the sensors that they had there in the Russell Senate Office Building attic.

ZAHN: Mike, please stand by.

And once again, as we are cautioned to all take a deep breath before we draw any conclusions here, I think it is important to remind all of you of something Jeanne Meserve just reported. That it is not uncommon in the Capitol for police there to get three reports a day of suspicious powders.

This of course is something different. We're not talking about powders. We're talking about the potential of nerve agents.

Let's turn to Jeanne Meserve and see what else she has got-- Jeanne.

MESERVE: Paula, I just talked to a D.C. Fire official who was on the scene who tells me he is very comfortable in saying that they do not have anything serious here.

This person tells me that the HAZMAT teams have gone into the building. They've had handheld chemical detectors. They have gone through with various types of machine, various kinds of technology, and they've have not gotten any positive hits at this point in time.

He says those teams have come out. They're now going through decontamination. Those tubes we heard about do contain air samples, he says. Those air samples are taken to the lab. His estimate is it is going to be about a half an hour before they have a final result.

In the meantime, those folks are being held in the garage but simply as a precaution until they get the final all-clear on that last set of tests.

ZAHN: And of course we're all hoping that this ends up not being something very serious, but let's once again help remind all of us who are trying to make sense of this what we could be looking at.

As we understand it, Jeanne, these monitors are so sensitive now that even something like a trace amount--someone was saying even cleaning fluid or fertilizer--could have set off this alarm.

MESERVE: Right. As somebody just said to me our greatest strength is our greatest weakness. We want a machine that's very sensitive. We want a machine that will pick up small traces of something that's dangerous, but the flip side of that is often they pick up something that in the end turns out not to be dangerous at all.

There also of course is the possibility that you have a detector that's malfunctioning in some way.

ZAHN: And when you talk about these hazardous materials teams now that are combing through the Russell Office Building with what you described as handheld chemical detectors, how accurate are those detectors?

MESERVE: I'm led to believe that they're quite accurate and that there are a couple of different technologies that could be used. And so they can cross-check one technology against the other. One may give the all-clear in a certain instance another other may alarm.

In this case, none of the technologies are indicating that they have anything dangerous that they're dealing with.

ZAHN: OK. Jeanne, please stand by.

Let's quickly go back to Mike Brooks, who is our security analyst.

I don't know if you're breathing a sigh of relief yet, maybe it's too early, but I guess when you have D.C. legitimate sources telling Jeanne Meserve this does not appear to be anything serious upon some of these teams having come in and gone out with these handheld detectors. I hope you think this is good news. BROOKS: No, it's very good news, Paula. You know, I was part of the FBI Joint Terrorism Task Force there in Washington, D.C., and actually I used to be part of the team that would respond and check these things out.

And I can tell you that the handheld -- the technology that they have in handheld detectors now has come a long way, and if they're pretty comfortable with that then I'm very comfortable with that having used those in the past.

And both the U.S. Capitol Police and D.C. Fire Department has materials unit, which is a also very, very professional unit. If they say that then I feel very comfortable that most likely it was a false positive and things will probably be back to normal in fairly short order there at the U.S. Capitol.

ZAHN: And I am hoping that we are confirm shortly is if in fact the alarm that was triggered in the attic of the Russell Office Building was the so-called positive test and not in fact a positive test on materials that was done.

BROOKS: Well, you know, there are a number of other things depending on what is going on at this time of night at the Russell Senate Office Building. There are other chemicals that can give the false positive as this is sucked up into the filters and goes through the detector system.

You now, it tests for certain things, proteins and other things, don't want to give away any secrets, but false positives happen on a regular basis. My sources tell me that it happens on a regular basis there at the U.S. Capitol. So this could be another false positive.

ZAHN: And that's why you got, Mike Brooks, some 200 folks underground right now in a parking garage, including or plus 12 senators in addition to those 200 staffers. They have been told by Capitol Police they will not be able to leave that area for at least an hour until Capitol Police can confirm that the coast is clear.

But Jeanne Meserve just confirming her sources are saying it doesn't appear at this hour that this is something serious or just a false positive due to very sensitive detectors.

Thanks so much for joining us until now. Our coverage of this breaking news continues with Larry King -- Larry.

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