A man has been shot dead in Oregon as a large procession of supporters of President Trump clashed with Black Lives Matter protesters in Portland.
Images from the scene showed medics trying to save the man, who appeared to be white.
Police have not given an identity or specified whether the shooting was directly linked to the clashes which broke out in a downtown area.
Portland's streets have been the scene of frequent protests in recent weeks.
The city has become a focus for demonstrations against police brutality and racism since the police killing of African-American George Floyd in Minneapolis on 25 May triggered a wave of national and international outrage.
Federal forces were sent by President Trump to Portland in July in what was described as a move to prevent violence but later withdrawn.
Acting homeland security chief Chad Wolf refused to rule out sending them back when pressed on ABC's This Week.
"I believe all options continue to be on the table, specifically as we talk about Portland," he said.
What is known about the shooting?
The latest pro-Trump rally was on the third Saturday in a row.
In a statement, Portland police said: "Portland Police officers heard sounds of gunfire from the area of Southeast 3rd Avenue and Southwest Alder Street. They responded and located a victim with a gunshot wound to the chest."
The man did not survive, they said.
Oregon Live reported that "camouflage gear" with "thin blue line patches" was seen next to the body - a common sign of support for the police.
The man was wearing a hat linked to far-right group Patriot Prayer, the New York Times reports.
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Another image shows police trying to restrain a man who was apparently with the person who was shot.
Pivotal week for 'law and order' Trump
Peter Bowes, BBC North America correspondent
The continuing violence on US streets brings into focus the evolving tone of Donald Trump's election campaign - criticising cities run by Democrats, where much of the trouble has occurred, and framing himself as the law and order president.
Portland has been the epicentre of Black Lives Matter protests ever since the police killing of George Floyd, but the convergence of pro-Trump supporters, in large numbers, with anti-racism demonstrators marks a volatile escalation.
Tweeting "LAW & ORDER!!!" hours after the latest disturbances, Mr Trump makes it clear that the issue will dominate his appeal to the American people for a second term in office.
This could be a pivotal week. On Tuesday the president will head to Kenosha, in the political swing state of Wisconsin, where violent protests followed the police shooting of Jacob Blake. The stated reason is for Mr Trump to meet local police and "survey damage from recent riots".
Many Americans will be watching to see if the president also reaches out to Mr Blake and his family and for any expressions of empathy for those who're angry about police brutality.
What was the background to the shooting?
The shooting came amid fights between the Trump supporters and BLM protesters in the city centre.
Tension rose after a convoy of some 600 vehicles flying flags and carrying an estimated 1,000 Trump backers gathered at a mall in Clackamas county on the outskirts before entering Portland's downtown.
Video showed some people firing what local media described as pepper spray and pellets at BLM groups who had tried to prevent them entering the city by blocking streets.
Police reported "some instances of violence" between "demonstrators and counter-demonstrators" and said some arrests had been made.
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The violence followed last week's Republican convention which formally anointed Mr Trump as the party's presidential candidate.
Accepting the nomination in a speech on the White House lawn, he sought to characterise Portland as another Democratic-run city prey to "rioting, looting, arson and violence".
The clashes also come in the wake of the shooting by police of Jacob Blake. He was hit in the back seven times and seriously wounded by an officer in Kenosha, Wisconsin, as he leaned into a car.
Why is Portland a flashpoint?
Some protests in Portland over George Floyd's death have been marred by violence, arson, damage to property, arrests and allegations of police brutality.
In July, federal officers drew strong criticism for cracking down on crowds - against the wishes of the local authorities - who had gathered in the city. Federal officers in unmarked vehicles appeared to forcefully seize protesters from the streets and detain them without justification.
The Trump administration described the protesters as a violent mob, but city officials drew a distinction between peaceful demonstrators and smaller groups bent on making trouble.
Portland has also seen violence between far-right groups, such as Proud Boys and Patriot Prayer, and left-wing counter-demonstrators known as antifa, or anti-fascist movement.
