This story is still developing:

 

An alarm went off at the Russell Senate Office Building, which is located a few blocks from the main Capitol building. The alarm, which none of the staffers had ever heard before, was apparently an air detection alarm that indicated some sort of nerve agent possibly in the air.

 

A first field test came back positive for an agent, but the second came back negative. Results for a third test will be available in 30-40 minutes.

 

Right now, 200 or more staffers and at least 8 Senators are being held in the parking garage of the Senate Office Building. The senators include Byrd, Hagel, Thune, and others.

 

I will update this thread once more news is available.

They gave the all clear.

 

WASHINGTON - Eight senators were among 200 people who were held in a Capitol parking garage Wednesday night after a security sensor indicated the presence of a nerve agent in their office building. Later tests proved negative.

 

Test results have been cleared and all test results are negative, so that's very good news," said Capitol Police Sgt. Kimberly Schneider.

 

The all-clear came three hours after an air-monitoring sensor indicated a suspicious substance in the attic of the Russell Senate Office Building. It initially tested positive as a nerve agent.

 

Lawmakers, aides and other personnel were evacuated to the nearby West Legislative Garage shortly after 6:45 p.m. EST as police conducted several other tests before concluding that it was a false alarm.

 

"We had this warning system work," said Sen. Jeff Sessions (news, bio, voting record), R-Ala., one of those in the garage. "People in the building followed the directions promptly. There was no panic, no running, no upset or anything like that."

 

Police said none of the people who were evacuated to the garage showed any signs, such as a runny nose, of exposure to a nerve agent.

 

"One of the alarm systems that tests air quality went off with a positive reading, and then it went off again with a positive reading, so I guess they thought it was serious enough that they had to take very aggressive action," Sen. Judd Gregg (news, bio, voting record), R-N.H., another of the senators evacuated from the building, said while speaking on a cell phone from the garage.

 

Gregg said everyone was eager to go home, but understood the need for the delay.

 

"I started out flying in Air Force One and ended up in the garage with 200 of my closest friends," he said. Earlier in the day, Gregg accompanied President Bush on a brief visit to New Hampshire.

 

Kyle Downey, a spokesman for Sen. John Thune, R-S.D., said he was in his office in the Russell building when an alarm went off. He said he and everyone else in the building tried to leave, but police directed them into an underground parking garage across the street. There, he said, police officers reassured the crowd of about 150 that such alarms are pretty common. They handed out water and gave folks regular updates.

 

Downey said the crowd remained calm and "milled around," some talking about the annual Washington Press Club Foundation dnner they were missing elsewhere in the district.

 

"Everybody was in a fine mood, everybody was calm. ... Everybody's been up here for a few years now. What does panic get you anyway?

 

"I'd also give the police a lot of credit. They were very clear about everything."

 

http://news.yahoo.com/s/ap/20060209/ap_on_...itol_evacuation

That's good news.