Authorities ordered a lockdown of congressional offices on Capitol Hill Thursday afternoon after shots were reportedly fired in the area. The Senate sergeant-at-arms said via Twitter at around 3 p.m. that the lockdown was lifted.

(Shawn Thew/EPA) - People run after hearing gunshots near the US Capitol. (Shawn Thew/EPA) – People run after hearing gunshots near the US Capitol.

On Thursday afternoon, U.S. Capitol Police issued warnings for occupants of the buildings to “shelter in place” and to “close, lock and stay away from external doors and windows.”

Senate Majority Leader Harry Reid (D-Nev.) told a CNN reporter “one injury.”

Rep. Gerry Connolly (D-Va.) said he was told by a sergeant-at-arms that a suspect had been apprehended.

Connolly was standing on a balcony of the U.S. Capitol with Rep. Matt Cartwright (D-Pa.) when they heard two bursts of gunfire coming from the direction of the Rayburn Office Building.

“It was almost like two very rapid fire bursts, very loud,” he said. “They were clearly coming from the direction. That’s when we saw people fleeing, and we realized this was no fireworks. It sounds liked the first volley of a 21 gun salute.”

Connolly said he could see people fleeing away from the Rayburn building and police officers running towards it before he was shepherded back into the building.

Other witnesses reported that the shots occurred near the Hart Senate building. The sound of gunfire could have echoed off the congressional offices, creating confusion about precisely where the noises were coming from.

* Rosalind Helderman reported from Capitol Hill