The Columbine High School massacre was a school shooting that occurred on April 20, 1999, at Columbine High School in Columbine, an unincorporated area of Jefferson County, Colorado, United States. In addition to the shootings, the complex and highly planned attack involved a fire bomb to divert firefighters, propane tanks converted to bombs placed in the cafeteria, 99 explosive devices, and car bombs. The perpetrators, senior students Eric Harris and Dylan Klebold, murdered 12 students and one teacher. They injured 21 additional people, and three more were injured while attempting to escape the school. After exchanging gunfire with responding police officers, the pair subsequently committed suicide.