Clashes between US President Donald Trump supporters and Black Lives Matter protesters flared on Saturday in Portland Oregon.
One person was shot and killed but it is unclear if his death was linked to the clashes.
A large caravan of Trump supporters was confronted by counter-demonstrators in the city.
An Associated Press freelance photographer heard three gunshots and then observed police medics working on the body of the victim, who appeared to be a white man.
The photographer said the man was wearing a hat bearing the insignia of Patriot Prayer, a right-wing group whose members have frequently clashed with protesters in Portland in the past.
Police said the man was shot in the chest at around 9pm Pacific. He was not immediately identified and it is unclear who shot him.
Police have appealed for information.
“This violence is completely unacceptable and we are working diligently to find and apprehend the individual or individuals responsible,” Chief Chuck Lovell said.
Portland has seen nightly protests for more than three months after the police killing of Black man George Floyd in Minneapolis.
Many of them end in vandalism and violence. Hundreds of demonstrators have been arrested by local and federal law enforcement.
In the two hours following the shooting, protesters gathered downtown and there was sporadic fighting and vandalism, police said.
Trump's 'law and order' campaign
The caravan arrived downtown just as a protest planned for Saturday was getting underway.
Police said several people were arrested before the shooting.
The chaotic scene came two days after Trump invoked Portland as a liberal city overrun with violence in a speech at the Republican National Convention as part of his “law and order” re-election campaign theme.
The caravan marked the third Saturday in a row that Trump supporters have rallied in the city.
The pro-Trump rally’s organiser, who recently coordinated a similar caravan in Boise, Idaho, said in a video posted on Twitter on Saturday afternoon that attendees should only carry concealed weapons and the route was being kept secret for safety reasons.
The caravan had gathered earlier in the day at a suburban mall and drove as a group to the heart of Portland. As they arrived in the city, protesters attempted to stop them by standing in the street and blocking bridges.
Videos from the scene showed sporadic fighting, as well as Trump supporters firing paintball pellets at opponents and using bear spray as counter-protesters threw things at the Trump caravan.