Three students killed, five wounded by Michael Carneal. April 20, 1999: Littleton, Colorado 14 students (including shooters) and one teacher killed, 27 others wounded at Columbine High School . February 27, 2012: Chardon, Ohio Chardon High School, T.J. Lane, 17, took a .22-caliber pistol and a knife to Chardon High and firing 10