U.S. Capitol building evacuated after alarm sounded

Darkness sets in over the U.S. Capitol building hours before U.S. President Barack Obama is set to deliver his State of the Union address to a joint session of Congress on Capitol Hill in Washington January 24, 2012. REUTERS/Jonathan Ernst

WASHINGTON (Reuters) - The U.S. Capitol building was being evacuated after an audible alarm was sounded, U.S. Capitol Police said on Tuesday. No other details were immediately available on the cause for the alarm, although law enforcement was checking on the possibility of a fire, a police official said. (Reporting By Richard Cowan; Editing by Bill Trott)