Update: Capitol Police say fire alarm prompted Cannon Building evacuation By fox5dc.com staff Published October 25, 2018 News FOX 5 DC Facebook Twitter Print Email WASHINGTON - U.S. Capitol Police say the Cannon Building was evacuated after a malfunctioning electrical panel prompted a fire alarm on Thursday. They said there were no reports of fire in the building, and it was cleared for re-entry around 1 p.m.