Two students kill 13, injure 23 at Columbine High School on April 20, 1999

Published: Apr. 20, 2026 at 7:34 AM CDT
In 1999 it was unthinkable for someone to attack a school - that changed on April 23, 1999 when two Littleton, Colorado students entered Columbine High School armed with guns and explosives.