Man shoots, kills self near US Capitol

A man holding a protest sign shot and killed himself near the steps of the US Capitol at the height of tourism season in Washington, triggering a brief 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 in the afternoon.

US Capitol Police Chief Kim Dine said no shots were fired by police. His force investigated a backpack and case the man had with him before reopening the legislative building and its visitor center.

Dine said the shooting was not terrorism-related, declining to comment further on the man's identity or his motive pending an investigation.

The FBI, Secret Service and local police are investigating the shooting.

"We potentially know who he is but obviously we have to secure that and verify it," Dine said.

Washington is in the middle of one of its peak tourism seasons as visitors flock to view the city's famous cherry blossoms.

Groups of tourists milled around the police tape closing off a large area filled with emergency response vehicles.

The shooting took place just after 1:00 pm (1700 GMT) and the lockdown ended nearly three hours later.

The entrance for tourists is on the opposite side of the building from where the shooting occurred, but visitors frequently walk across much of the Capitol grounds.

- Tourists, visitors witness shooting -

Several visitors tweeted about seeing the shooting.

"Just ran from the capital building after a protester shot himself right next to us," tweeted one visitor.

Another wrote: "Just witnessed someone shoot themselves at the U.S. Capitol.. Whole place is on lockdown."

Most of the city's downtown area was not impacted by the shooting that closed the Capitol.

Washington security bodies have dealt with a number of incidents recently that have raised questions about their ability to secure the US capital.

Late last month, US police opened fire and one suspect died after two men dressed in women's clothing tried to ram their car onto the grounds of the National Security Agency outside Washington.

A mentally disturbed US veteran jumped over the White House fence and ran into the US president's mansion with a knife in September. An investigation found a number of lapses in Secret Service security.

Separately, Secret Service agents were found to have driven into White House barricades after a night of drinking, provoking the ire of Congress that has called into questions the force's overall capabilities.

A small, private drone crashed into the grounds of the executive mansion in January, leading authorities to ban their use within the capital.

The US Capitol Police secures a network of buildings and open areas surrounding the Capitol, while the Secret Service provides protection to the White House.