A far-right activist sprays mace at a TV news crew security guard moments before being shot dead, as political turmoil continues to rage in the US.
The shooting happened after clashes between a far-right “patriot muster rally” and anti-fascist protesters.
In footage filmed seconds before the killing, the victim is seen among a group arguing with a rival protestor.
He then pulls his Stars and Stripes neckerchief over his face as he moves off-camera – where pictures show him appearing to clash physically with the private security guard.
On the video, a single shot is heard – and further pictures show the man lying motionless on his back, the mace can beside him, as the security guard keeps his handgun trained on him.
The guard himself is then seen on his knees, hands in the air, as armed police surround him. Two guns were recovered at the scene.
Police in Denver, Colorado, said the death was being treated as homicide.
Chief investigator Joe Montoya said: “There was a verbal altercation that transpired at the area of the shooting.”
The incident took place as the rally, close to Denver Art Museum, was coming to an end shortly after 3.30pm local time on Saturday.
Earlier, a counter-protestor burned a blue-coloured Stars and Stripes flag, used by pro-police groups, setting it alight at the feet of nearby officers.
The rally was one of many such events across the US since the death of George Floyd after a white officer knelt on his neck in Minneapolis in May.
In July a “Back the Blue” rally in support of police was organised by John Tiegen, an ex-Marine and private security guard, which descended into chaos when opposing groups clashed.
On Saturday, Tiegen had summoned followers to the Denver rally with the slogan: “Stand up, show up.”
It echoed Donald Trump’s refusal to condemn white supremacists the Proud Boys, telling them instead to “stand back and stand by”.
Protests in the US since George’s death have led to a string of killings.
Two anti-racism protesters were shot dead in Kenosha, Wisconsin, in August, allegedly by a 17-year-old boy with a semi-automatic rifle.
Days later in Portland, Oregon, a man shot and killed a far-right activist. He was later shot dead by police.
