Columbine High School shooting was one of the deadliest mass shootings in United States history. On April 20, 1999, two teenagers killed 13 people and wounded more than 20 at Columbine High School in Littleton, Colorado. The incident drew worldwide attention. It led to widespread discussion over gun control and the prevention of school violence.
The attack.
Eric Harris and Dylan Klebold were seniors at Columbine High School in Littleton, a suburb of Denver. At about 11 a.m. on April 20, the two arrived at the school with guns and homemade bombs. They set bombs in the school’s cafeteria, kitchen, and parking lot, but the bombs did not go off as planned. Harris and Klebold began shooting just as they were about to enter the school. They continued shooting as they walked through the school. They killed a teacher and 12 students and wounded more than 20 others. Soon after 12 p.m., the pair committed suicide in the school’s library.
Investigations and aftermath.
Police investigations revealed that Harris and Klebold had planned the attack to be primarily a bombing. Harris was the main planner. The pair had built bombs and acquired guns and ammunition for more than a year. Police said that if the bombs had been constructed properly, the attack could have killed several hundred people. 
Law enforcement experts posed a number of theories about the killers’ motives. Early theories proposed that Harris and Klebold belonged to an antisocial student group and sought revenge on bullies. Experts later concluded that the two wanted to become famous for conducting a spectacular mass killing.
In the years following the shooting, police departments adopted new procedures for handling attacks like the one at Columbine. In 2007, a memorial to those killed at the school was dedicated at a nearby park.
See also School violence .
