AP
 
Washington, May 27:  A phone call reporting gunfire — apparently a false alarm — led police to briefly shut down the Capitol on Friday and search the largest House office building floor by floor as staff members and a few lawmakers were kept inside.

Officers with rifles stood by outside, and ambulances arrived. But in the end police said there were no arrests, injuries or confirmation of any gunfire in the garage of the Rayburn House Office Building.

The report originated with Rep. Jim Saxton, R-N.J., his press secretary said. Saxton heard what he thought were gunshots and had a member of his staff call Capitol Police, said spokesman Greg Keeley.

Capitol Police spokeswoman Sgt. Kimberly Schneider said police were investigating a "plausible explanation" that the day's events resulted from noise made by construction workers in the Rayburn garage. "In doing their routine duties, they made some sort of a noise that sounded like shots fired. So it was a valid call," she said.

On high alert, police lined the street between the Capitol and the Rayburn building, rifles prominently displayed, and four ambulances, two firetrucks and other emergency vehicles were on the scene.

Police methodically searched the sprawling building, where congressional staff members had locked themselves into their offices as a precaution.

"Right now we want to err on the side of caution," Schneider said before the all-clear, which came at mid-afternoon, some four hours after the first report. "Lives could be at risk. If we have a gunman in the building we certainly want to find him. It's premature to assume that it may not be a gunman."

The Senate was in session at the time, but the House was not as most lawmakers had left for the Memorial Day recess.

Indeed, one congressional staff member was taken to a hospital after suffering a panic attack during the lockdown and search, Schneider said. The woman was released a short time later.

The search was a complicated one. The building, which covers a long city block, is connected to a second office building by an underground tunnel. That building, in turn, is connected to the Capitol by a second underground tunnel.

The Rayburn House Office Building was completed in early 1965 and is the third of three constructed for the House of Representatives. It has four stories above ground, two basements and three levels of underground garage space.

Nearly two hours after the first alert, Capitol police sent an e-mail message to occupants of the office building saying they would soon begin a floor-by-floor search.

Usually teeming with visitors, Capitol Hill was uncharacteristically quiet. Although it was the start of a holiday weekend, tourists were few.