Police are "still working" on the bomb threat investigation near the US Capitol, according to a tweet.
Capitol Police Chief Tom Manger said in a news briefing earlier that officials continue to negotiate with a man who says he has a bomb in a pickup truck.
"We don't know what his motives are at this time," Manger said.
Two Library of Congress buildings — the Jefferson and the Madison — and the Cannon House Office Building were evacuated due to the suspicious vehicle, according to alerts sent to staffers viewed by CNN.