The Columbine High School massacre occurred on Tuesday, April 20, 1999, at Columbine High School in Columbine, an unincorporated area in Jefferson County, Colorado, United States, near Denver and Littleton. Two students, Eric Harris and Dylan Klebold, embarked on a massacre, killing 12 students and a teacher, injured 21 others, while 3 were injured while attempting to escape, before committing suicide. It is the fourth-deadliest school massacre in United States history, after the 1927 Bath School disaster, 2007 Virginia Tech massacre and the 1966 University of Texas massacre, and the deadliest for an American high school.
The massacre provoked debate regarding gun control laws, the availability of firearms in the United States, and gun violence involving youths. Much discussion also centered on the nature of high school cliques, subcultures and bullying, as well as the role of violent movies and video games in American society. The shooting also resulted in an increased emphasis on school security, and a moral panic aimed at goth culture, social outcasts, the gun culture, the use of pharmaceutical anti-depressants by teenagers, violent films and music, teenage internet use, and violent video games.
Early warning signs began to surface in 1996, when Eric Harris first created a private website on America Online. The original site was set up to host Doom levels that he and Dylan Klebold had created, mainly for friends. Harris also began a blog on the site, which included jokes and small journal entries concerning his thoughts on parents, school, and friends. By the end of the year, the site contained instructions on how to cause mischief, as well as instructions on how to make explosives, and logs of the trouble he and Klebold were causing. Beginning in early 1997, the blog postings began to show the first signs of Harris's ever-growing anger against society.