Salt Lake City police are investigating the roles of two self-described "peacekeepers" following a fatal shooting at Saturday's protest that left one person dead and another injured, raising questions about unauthorized security at public demonstrations.

A bystander was fatally shot after security members at the demonstration confronted a man who was running toward the crowd with an AR-15-style rifle, the police said.

An innocent bystander at a “No Kings” protest in Utah was shot and killed by a “peacekeeper” who was aiming for a different man pointing an AR-15-style rifle toward the crowd, witnesses told Salt Lake City police.