Columbine High School massacre was a school shooting and attempted bombing that occurred on April 20 , 1999 , at Columbine High School in Columbine , Colorado , United States . The perpetrators , twelfth grade ( senior ) students Eric Harris and Dylan Klebold , murdered 12 students and one teacher . Ten students were killed in the school library , where the pair subsequently committed suicide . 21 additional people were injured with gunshots and gunfire was also exchanged with the police . Another three people were injured trying to escape the school . At the time , it was the deadliest school shooting in United States history . The crime has inspired several copycats , and " Columbine " has become a byword for a school shooting . In addition to the shootings , the attack involved several homemade bombs . Two of these were placed in the cafeteria , powerful enough to kill or seriously injure all people within the area , although they failed to detonate . Their cars in the parking lots were made into bombs which also failed to detonate , and at another location away from the school , two bombs were set up as diversions , only one of which partially detonated . The motive remains unclear , but the pair planned the massacre for around a year and wished to become infamous ; and for the massacre to rival the Oklahoma City bombing and cause the most deaths in United States history . '' USA Today '' referred to the attack as " planned as a grand , if badly implemented , terrorist bombing "
Oklahoma City bombing
Oklahoma City bombing
Columbine High School massacre