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Columbine High School massacre

A mass killing case documented in Columbine, Colorado, United States, during 20 Apr 1999.

Place
Columbine, Colorado, United States
Date
20 Apr 1999
Status
Investigation closedThe investigating authority has ended its active investigation. This does not necessarily mean a court resolved the case.
Sources
2 cited sources

Updated 23 Aug 2026

Overview

Case overview

On April 20, 1999, high school senior students Eric Harris and Dylan Klebold murdered 13 students and one teacher in a school shooting and attempted bombing at Columbine High School in Columbine, Colorado, United States. The police were slow to enter the school and were strongly criticized for not intervening during the shooting. [1]

At 2:15 p.m., student Mike Rotole placed a sign in the window, reading "1 bleeding to death", in order to alert police and medical personnel of Dave Sanders's location in the science room. Gardner reported on his police radio, "Shots in the building. [2]

A black and white still image taken from the security video of Columbine High School during the shooting, showing Eric Harris and Dylan Klebold.
A black and white still image taken from the security video of Columbine High School during the shooting, showing Eric Harris and Dylan Klebold.Columbine High School · Public domain · View original ↗
Standard chronology

Key events

5 sourced milestones

Major events in the case, shown in chronological order.

  1. The attack takes place

    Two students attacked Columbine High School, killing twelve students and one teacher before dying by suicide inside the school.

    Source: Wikipedia ↗

  2. Authorities begin formal reviews

    Colorado officials and Jefferson County agencies began examining the warning signs, emergency response, and evidence left by the attackers.

    Source: Wikipedia ↗

  3. A concealed draft affidavit becomes public

    Reporting disclosed a previously concealed draft search affidavit concerning Eric Harris, prompting scrutiny of the sheriff's pre-attack response.

    Source: Wikipedia ↗

  4. A grand jury report is released

    A grand jury investigation into the handling and concealment of pre-attack records issued its final public report.

    Source: Wikipedia ↗

  5. Authorities publish the final investigative report

    The Jefferson County Sheriff’s Office released its final investigative report after the two perpetrators died by suicide at the school, documenting the attack and the evidence recovered by investigators.

    Source: Wikipedia ↗
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