High school students Eric Harris and Dylan Klebold used multiple IEDs during the Columbine High School massacre on April 20 , 1999 , including two large propane bombs that were placed in the cafeteria , powerful enough to kill or injure everyone inside the room , along with pipe bombs , molotov cocktails , and also two car bombs , designed to attack first responders and news reporters responding to the initial bombing . Both propane bombs and both car bombs failed to detonate correctly . They then went on to shoot and kill 13 people before committing suicide . If all bombs detonated , there could have been hundreds killed in the massacre , but nobody was injured by any of the explosives during the massacre . The pair had planned to exceed the death count during the Oklahoma City bombing four years earlier
Columbine High School massacre
Columbine High School massacre
Improvised explosive device