PORTLAND, OREGON: Police shot and killed an anti-fascist activist on Thursday as they moved in to arrest him for the alleged fatal shooting of a right-wing activist in Portland, Oregon, last weekend, officials said.

Michael Reinoehl, 48, was wanted on a charge of murder when members of a fugitive task force shot him dead in Olympia, Washington after he left an apartment building and got in a car, according to police.

"The suspect produced a firearm, threatening the lives of law enforcement officers," a US Marshals Service spokesman said in a statement.

Thurston County Sheriff's Office, which is responsible for investigating the incident, said it had not confirmed Reinoehl was armed or whether he fired any shots.

"There were shots that were fired from the task force into that vehicle and the suspect fled from the vehicle on foot and there were additional shots that were fired," said Lieutenant Ray Brady of the Sheriff's Office.

Portland Police earlier on Thursday issued a warrant for Reinoehl's arrest and asked the US Marshals to locate him.

"They lit his ass up," bystander Jashon Spencer said in an online video. "It sounded like fireworks it was that many shots."

Reinoehl, who had provided security for Black Lives Matter protests in Portland, was allegedly involved in the shooting of Aaron Danielson on Saturday night, the US Marshal's Service said.

Danielson, 39, was among a caravan of supporters of President Donald Trump who rode in pickup trucks into downtown Portland and clashed with protesters demonstrating against racial injustice and police brutality.

Portland has seen escalating clashes between right- and left-wing groups in recent weeks following nearly 100 days of protests since George Floyd, a Black man, died in Minneapolis on May 25 after a white police officer knelt on his neck.

Reinoehl died only hours after Vice News broadcast a video in which he appeared to admit he shot Danielson and said he acted in self-defence.

"I had no choice. I mean, I, I had a choice. I could have sat there and watched them kill a friend of mine of color. But I wasn't going to do that," he said in the video, adding he feared he would be stabbed.

Reinoehl was previously cited for carrying a loaded gun at a July 5 Portland protest, resisiting arrest and interfering with police, according to The Oregonian newspaper. The allegations were subsequently dropped, the newspaper reported.

In social media posts Reinoehl described himself as a professional snowboarder, a US Army veteran and "100% ANTIFA."

Antifa is a largely unstructured, far-left movement whose followers broadly aim to confront those they view as authoritarian or racist.

Reinoehl said he was prepared to fight to change the "course of humanity.

"It will be a war and like all wars there will be casualties," he said in a June 16 Instagram post.

In July, the Trump administration deployed federal forces to Portland to crack down on the protests.

Trump signed a memo on Wednesday that threatened to cut federal funding to "lawless" cities, including Portland.

On Thursday he had demanded that police arrest Reinoehl.

"Why aren't the Portland Police ARRESTING the cold blooded killer of Aaron “Jay” Danielson. Do your job, and do it fast. Everybody knows who this thug is. No wonder Portland is going to hell!," he tweeted.