"Here is a list of mass shootings in the U.S. that featured AR-15-style rifles during the last 35 years, courtesy of the Stanford Geospatial Center and Stanford Libraries and USA TODAY research:... June 12, 2016: Omar Mateen, 29, used an AR-15 style rifle (a Sig Sauer MCX), and a 9mm Glock semi-automatic pistol to kill 49 people and injure 50 at an Orlando nightclub before he was killed."