WASHINGTON (REUTERS, AFP) - A man who claimed to have a bomb in a pickup truck near the US Capitol surrendered to police on Thursday (Aug 19) after a standoff that paralysed a swath of Washington for more than five hours.

Capitol police chief J. Thomas Manger told reporters that the man, identified as Floyd Ray Roseberry, parked his vehicle on a sidewalk outside the US Library of Congress at about 9.15am EDT (9.15pm Singapore time) and told an officer who approached him that he had a bomb while holding what appeared to be a detonator.

Police shut down streets and evacuated nearby buildings as they negotiated with Roseberry, 49.

"He gave up and did not resist and our folks were able to take him into custody without incident," Manger said.

Police said they found possible bomb-making materials, but no bomb, in the truck.

Two law enforcement sources, speaking on condition of anonymity, said it appeared Roseberry had acted alone.

A video livestreamed on Facebook showed Roseberry, a bald white man with a goatee, speaking inside a black truck parked on a sidewalk.

"The revolution's on, it's here," Roseberry said in the video, while appearing to hold a large metal cannister on his lap. "I'm ready to die for the cause."

His ex-wife, Crystal Roseberry, told Reuters that he had been diagnosed with schizophrenia and had threatened her with firearms in the past.

She said she divorced him about eight years ago.

"He's crazy. He pulled a gun on me and his sister, and shot at me numerous times," said the woman.

Facebook removed Roseberry's profile and deactivated the livestream after several hours.

Police said they did not know his motive.

Federal agents raided his home in Grover, North Carolina, during the standoff in the US capital.

Neighbours described Roseberry as a Republican who was known to occasionally wear a red "Maga" hat to show his support for former president Donald Trump. He also criticised Democrats on social media.

They said Roseberry would set off explosives in his yard and disrupt deer hunters by shooting his gun repeatedly.

Benjamin Christopher told Reuters the explosions upset him and his wife, who both served in Afghanistan.

"Me and my wife, we're both Afghanistan vets, and we have both been injured in Afghanistan via bombs, so it wasn't sitting too well with my wife," he said.

The normally busy Capitol complex was relatively deserted on Thursday, with the US House of Representatives and Senate out of session.

Police blocked off roads surrounding the Capitol complex as fire and rescue trucks and federal agents headed to the area.

Nearby buildings, including the US Supreme Court, were evacuated.

Tensions have remained high on Capitol Hill more than seven months after the deadly Jan 6 insurrection, when supporters of then-president Donald Trump stormed the US Capitol, fought with police, and sought to block certification of the presidential election.

In April, a man rammed a car into barriers at the US Capitol, killing one Capitol Police officer before the attacker was shot and killed.

High-security fencing was erected in the area after the Jan 6 attack, but it was removed by mid-July.