A sore loser at a fist fight at the Titusville Peace in the City Rally returned with a firearm and began shooting at random. An armed bystander intervened and shot the shooter in the head and thereby prevented anyone else from being injured. The armed bystander was not arrested but the shooter was taken to the hospital for life threatening injuries.
https://www.zerohedge.com/news/2018-08-05/armed-bystander-takes-down-gunman-childrens-event
https://www.zerohedge.com/news/2018-08-05/armed-bystander-takes-down-gunman-childrens-event