These are the six deadliest mass shootings in U.S. history Columbine High School massacre In April 1999, seniors Eric Harris and Dylan Klebold fatally shot 12 students and one teacher, and wounded 21 others. Virginia Tech massacre Seung-Hui Cho shot and killed 32 people in two locations of the school's Blacksburg, VA. campus in 2007. Sandy Hook Elementary School massacre 20-year-old Adam Lanza killed his mother before driving to the school and fatally shooting 20 children and six staffers. San Bernardino shooting On Dececember 2, 2015 in San Bernadino, CA., married couple Syed Farook and Tashfeen Malin opened fire at a holiday party, killing 14 and wounding 22. Pulse nightclub massacre On June 12, 2016, Omar Mateen shot and killed 49 people and wounded more than 50 inside of Pulse Nightclub in Orlando, FL. OCTOBER 1, 2017 Suspected shooter Stephen Paddock left at least 58 dead when he opened fire at a country music festival in Las Vegas. Over 500 people were injured.