Denver police arrested the gunman, who was working for a local TV news crew, on suspicion of murder after a member believed to belong to the ‘Patriot Muster’ group was fatally wounded

The man on the left side of the photo was supporting the “Patriot Rally” (Image)

Shot dead at close range, this is the moment a private security guard killed a man as rallies between rival far-right and far-left activists erupted in violence.

Denver police arrested the gunman, who was working for a local TV news crew, on suspicion of murder after a member believed to belong to the ‘Patriot Muster’ group was fatally wounded.

The dead man maced the security guard, who then pulled out his handgun and shot him at 3.37pm on Saturday near the courtyard of the Denver Art Museum.

The shooting came as the protests between the two groups were winding down, officials said.

Video close to the incident shows what led up to the death.

A man wearing a “Black Guns Matter” T-shirt is seen loudly arguing with several men after allegedly being harassed by suspected “white supremacists”.