U.S. Rep Joe Courtney was on the phone with an under-secretary of defense when he heard the Capitol's warning system blaring Thursday afternoon.

"Tension is running high obviously because of the political environment. We just had a round of votes that I walked back from and was on a conference call," Courtney, D-2nd District, said 15 minutes after the shooting. "We have these really loud warning communications systems here with the Capitol Police and all of sudden they were blaring that there was a shooting on Capitol Hill. 'Stay in your offices' kept getting repeated over and over again."

Courtney said his office is on the other side of the Capitol campus; the shooting took place outside the Senate Hart Office Building. A staffer in Courtney's office checked in with the offices of U.S. Sens. Richard Blumenthal and Chris Murphy and was told everyone was fine there.

"For now I'm just staying hunkered down," Courtney said.

Courtney said he spoke with Rep. Rosa L. DeLauro, who was stuck on the floor of the House because of the lockdown.

"Capitol Police are everywhere," Courtney said. "The halls are pretty deserted. They don't want people walking around right now. In the middle of the day this place is usually buzzing with activity, people are walking around, going to meetings, heading to the floor. Now the halls are empty."

Courtney noted that the shooting on Sept. 16 occurred at the Washington Navy Yard, not far from the Capitol.

The lockdown was lifted around 3 p.m.