A man who was believed to be part of a peacekeeping team for the “No Kings” protest in Salt Lake City shot at a person who was brandishing a rifle at demonstrators, striking both the rifleman and a bystander who later died at the hospital, authorities said Sunday.

The man Utah police describe as an innocent bystander slain after gunfire broke out has been identified as Arthur Folasa Ah Loo.

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.