Factbox: Major shootings in the United States

Below are some of the worst shooting incidents in recent years, ranked by the number of dead, including the shooter: Virginia Tech April 16, 2007 - A gunman slaughters 32 people and himself at Virginia Tech, a university in Blacksburg, Virginia. Columbine April 20, 1999 - Two heavily armed teenagers go on a rampage at Columbine High School in Littleton, Colorado, shooting 12 students and a teacher and wounding more than 20 others before taking their own lives.