Shooting locks down US Capitol

US Capitol police shot a male suspect on Monday afternoon following reports of gunfire at the Capitol Visitors Centre, CNN reported.

A female civilian bystander was injured by shrapnel, but no US Capitol Police officers have been injured. The Capitol complex remains on lockdown.

No other suspects appear to be at large, according to a notice sent to Senate staffers.

"There has been an isolated incident at the US Capitol. There is no active threat to the public," the DC Police Department tweeted.

Police and firefighters swarmed the entrance of the visitor centre, which was packed this week with tourists, spring break visitors and school groups.

Congressional staffers were sent a notice to shelter in place, instructing them to lock doors and moved to assigned shelter areas. Those outside the buildings on the Capitol complex were told to "seek cover away from the area".

House Speaker Paul Ryan, who was not currently in Washington, has been briefed on the incident, according to his spokesman.

Senate Majority Leader Mitch McConnell was in Louisville and his staff is safe, his spokesman said.

The White House was also briefly locked down after an unrelated incident.