DENVER — A private security guard working for a local TV station was jailed in an investigation of first-degree murder in the deadly shooting of another man during dueling right- and left-wing protests in downtown Denver, police said Sunday.

Matthew Dolloff, 30, was taken into custody in connection with a clash that took place Saturday afternoon in Civic Center Park.

A man participating in what was billed a “Patriot Rally” slapped and sprayed Mace at a man who appeared to be Dolloff, the Denver Post reported, based on its photographs from the scene. The man identified by the newspaper as Dolloff drew a gun from his waistband and shot the other person, according to the Denver Post journalist who witnessed the episode.