Columbine High School Shooting

On April 20, 1999, two students at Columbine High School in Littleton, Colorado, carried out a planned attack on their school, killing twelve students and a teacher before taking their own lives. More than twenty others were wounded. Broadcast live as it unfolded, the assault became one of the most shocking events of the decade and the deadliest school shooting in the country up to that time.

The attack entered the national consciousness in a way earlier school shootings had not, in part because of the saturation television coverage and the chilling evidence the perpetrators left behind. In its aftermath, a wave of misconceptions spread — about the attackers' motives, about supposed targeting of particular groups, and about warning signs — that later investigations spent years correcting.

Columbine's most consequential legacy was in how authorities respond to such attacks. The slow, perimeter-based police tactics used that day were widely judged to have cost lives, and law enforcement nationwide adopted a new doctrine of immediately confronting an active shooter rather than waiting. Schools introduced lockdown drills, threat-assessment programs, and new security measures that became routine for a generation of students.

The event also intensified enduring national debates over gun access, mental health, bullying, and the influence of media — arguments that have recurred after each subsequent mass shooting without resolution. "Columbine" became a grim shorthand, the reference point against which a long and painful series of later tragedies would be measured.