Updated Oct. 3, 2013 at 7:42 p.m.

In the first few minutes of the Capitol Hill lockdown, GW students interns said they didn’t know if the shooter was inside or outside the building.

Sophomore Jordan Capizola, who works for Rep. Tom Rooney, R-Fla., said the Capital’s bell system, which usually rings when congressmen are about to vote on legislation, made a noise she and other staffers had never heard before.

She said she constantly checked Twitter for updates about the situation while she was waiting inside Rooney’s office, and that staffers listened to a police scanner to find out what was going on.

“We were all a little nervous because it’s something that doesn’t really happen often,” she said.

Sophomore Lincoln Moody said the people working in his office were immediately afraid when the alert system went off.

“When we heard alarms, we just thought the worst,” Moody, who works for a Democratic congressman from Texas, said. “We heard the alarms and we actually thought it was an active shooter in the hallway. They started yelling for people to get into the rooms.”

About five minutes after the lockdown started, they learned the shooter was outside for the news. The lockdown was lifted after about a half hour, but Moody said his staff remained in place even longer.

Police warned employees in the Capitol building at about 2:30 p.m. that gunshots had been reported in front of the building, and an email told Senate office staffers to shelter in place.

Brianna Gurciullo contributed to this report.