CNBC: “Staffers at a congressional office building were ordered to evacuate Thursday as U.S. Capitol Police investigated a report of a suspicious vehicle outside of the Library of Congress. The Capitol Police Twitter feed warned people to ‘please stay away from this area.'”
“People at the Cannon House Office Building received an alert telling them to leave that building and relocate to the Longworth House Office Building. ‘This is an ongoing investigation,’ a follow-up tweet from Capitol Police said. ‘We are monitoring this situation closely and will update this account as we get information we can release.'”