Authorities on the scene are negotiating with the suspect, according to two law enforcement sources. The pickup truck the man drove to the scene does not have license plates, sources say.
Two Library of Congress buildings — the Jefferson and the Madison — and the Cannon House Office Building are being evacuated due to a suspicious vehicle in the vicinity, according to alerts sent to staffers viewed by CNN.
Staffers in the Madison and Jefferson buildings on Thursday were alerted by email to remain calm and relocate — and not to exit toward First Street. Those in Cannon were advised to relocate to the Longworth House Office Building using the Capitol’s underground tunnels.
The Senate and House are not in session, and most lawmakers are not currently in their offices.
The Supreme Court has also been evacuated on the recommendation of US Capitol Police, according to a spokesperson for the court, which is closed to the public because of Covid-19.
This story has been updated with additional information.