Two student gunmen at Columbine High School in Littleton, Colo., killed 12 students and a teacher, wounded 23 others and placed bombs throughout the school before taking their own lives.
The two students, 18-year-old Eric Harris and 17-year-old Dylan Klebold, go on a carefully planned rampage, shooting their classmates and teachers at point-blank range with an arsenal of weapons.
It was the deadliest school shooting in U.S. history.
