Active shooter study: Semi-automatic rifles more deadly

AR-15 Assault Rifles Sold At Utah Gun Shop
Semi-automatic rifles are on display at a gun shop and range in Orem, Utah. Research published Tuesday, Sept. 11, 2018 in the Journal of the American Medical Association shows active shooters with semi-automatic rifles wound and kill twice as many people as those using non-automatic weapons.
George Frey | Getty Images