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.

Utah officials are investigating the role that so-called peacekeepers played in the killing of celebrated fashion designer Arthur Folasa Ah Loo on Saturday at the “No Kings” demonstration in Salt Lake City,

An estimated 10,000 people were in attendance at the “No Kings” rally that began in Pioneer Park and marched north through the downtown area, the Salt Lake City Police Department said. Gunfire was heard at around 8 p.m., with video posted online showing protesters fleeing in terror.