By Keith Coffman

DENVER (Reuters) – A security guard hired to protect a Denver television news crew covering opposing rallies of right-wing and left-wing political activists is being held in custody on suspicion of first-degree murder in the fatal shooting of a protester, police said on Sunday.

The deadly gunfire erupted on Saturday following a “verbal altercation” between the suspect and victim just as a “Patriot Rally” and a counter-demonstration dubbed a “BLM-Antifa Soup Drive” was drawing to a close, Denver Police division chief Joe Montoya said.

The suspected gunman, identified by police as Matthew Dolloff, 30, was arrested just after the shooting, which occurred in a courtyard outside an art museum, but he has not been formally charged, Montoya said.

The man shot to death was not immediately named by authorities, but the Denver Post identified him, according to the victim’s son, as Lee Keltner, 49, a Navy veteran who ran a hat-making business in the Denver area for many years.

“He wasn’t a part of any group,” the son, Johnathon Keltner, told the Post. “He was there to rally for the police department, and he’d been down there before rallying for the police department.”

Denver station KUSA-TV, an NBC affiliate, said in its own account posted online that Dolloff was contracted by KUSA through the Pinkerton security agency, and that one of the station’s news producers was with Dolloff during the altercation.

Pinkerton did not immediately respond to an email request for comment.

Denver police tweeted on Sunday they are unaware if Dolloff was affiliated with any political group but said he was not a protest participant.

An image of the incident captured by Denver Post photographer Helen Richardson showed a man spraying a chemical agent at another man pointing a handgun in his direction. Montoya said two guns were recovered from the scene.

Richardson said on Instagram that the shooting victim, who she said was with the patriot rally, and the other man “exchanged heated words” before violence ensued.

The “patriot hit the man in the face, then backed up to spray what looked like pepper spray at him,” Richardson wrote. “Literally in that split second the man who had gotten hit by the patriot pulled out a gun from his waistband and shot the patriot.”

By all accounts, nobody from the side of the Black Lives Matter and anti-fascist counter-rally was directly involved in the deadly confrontation.

Dolloff made his first court appearance on Sunday, where a magistrate judge ordered the arrest warrant affidavit sealed and ruled that the suspect be held without bond, local media reported.

(Reporting by Keith Coffman in Denver; Editing by Steve Gorman and Michael Perry)