A man shot and killed himself near the steps of the US Capitol at the height of tourism season in Washington, leading to a short lockdown of the congressional building.
Police said the man had a "social justice" protest sign with him when he produced a weapon and shot himself on the western side of the building.
No further details were available about the sign.
US Capitol Police Chief Kim Dine said his force investigated a backpack and case the man had with him before reopening the legislative building and its visitor centre.
Dine said the shooting was not terrorism-related, declining to comment further on the man's identity or his motive pending an investigation.
Washington is in the middle of one of its peak tourism seasons as visitors flock to view the city's famous cherry blossoms.
The entrance for tourists is on the opposite side of the building from where the shooting occurred.
Several visitors tweeted about seeing the man, but most of the city's downtown area was not impacted by the shooting.
