Congressional staffer arrested with gun inside US Capitol office building

A congressional staffer was arrested Thursday for carrying a gun into the Longworth House Office Building, U.S. Capitol Police said, after the incident caused authorities to issue a warning about a "security threat."

At approximately 7:40 am, officers spotted the image of a handgun in a bag on an x-ray screen at a checkpoint, a release said, and the staffer was tracked down four minutes later and arrested.

Jeffrey Allsbrooks, a staffer with the House Chief Administrative Office, was charged with carrying a pistol without a license, police said.

He told officers he forgot the gun was in his bag, they said.

"This case remains under investigation and the Department is looking into what happened before, during and after those four minutes," the release said.

An email giving the all-clear was sent about 7:58 a.m

Minutes earlier, Capitol Police had sent an email warning of a "security threat" inside the Longworth building, part of the Capitol complex, instructing staffers to seek cover inside offices.

The email warned staff of a "security threat inside the building" and instructs recipients to "move inside your office or the nearest office," "take emergency equipment and visitors," "close, lock and stay away from external door or windows" and to "remain quiet and silence electronics."