The Columbine High School massacre occurred on April 20, 1999 at Columbine High School in Jefferson County near Littleton, Colorado, United States. Two students, Eric David Harris, age 18, and Dylan Bennet Klebold, age 17, executed a planned shooting rampage killing 12 other students and a teacher before committing suicide. It is considered to be the third worst school shooting in U.S. history, the worst being the 2007 Virginia Tech shooting and the second worst being the 2012 Sandy Hook Elementary School shooting.