What Happened At Columbine Shooting?

Two students - Dylan Klebold and Eric Harris - went on a shooting spree at Columbine High School in Littleton, Colorado on April 20, 1999. They killed 12 students and 1 teacher before turning the guns on themselves, for a grand total of 15 casualties. 21 others were wounded.

It's the 4th deadliest school shooting in US history, only overshadowed by the Bath School disaster, the '07 Virginia Tech massacre, and the Clock Bell Tower shooting.