Capitol Hill police evacuated the area around the Library of Congress after reporting an alleged explosive device in a pickup truck.
The building is close to the Capitol and the Supreme Court.
Law enforcement also evacuated the Cannon House Office Building.
Congress is on vacation this week.
Due to the bomb scare in an area near the US Library of Congress on Capitol Hill, the Supreme Court headquarters, currently closed to the public due to the pandemic, was also evacuated as a precaution.