A Timeline of School Shootings Since Columbine

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Aliza Vigderman
Gabe TurnerChief Editor
Last Updated Jan 17, 2024
By Aliza Vigderman & Gabe Turner on Jan 17, 2024
  • Since 2015, school shooting incidents in the U.S. have skyrocketed compared to previous decades.
  • So far in 2023, there have been 198 shooting incidents at K-12 schools, six of which involved active shooters.
  • The majority of active shooter incidents since 1999 have happened in high schools (nearly 60 percent).

Since the Columbine massacre, there have been a total of 304 fatal school shootings and counting. We have charted the frequency and severity of this phenomenon in our timeline of school shootings in the U.S below.

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A Timeline of School Shootings Since Columbine

Though it wasn’t the first instance of violence inside an American school, the Columbine High School shooting has proven to be a watershed moment. In just the four years that followed the 1999 massacre, more than two dozen others were killed and even more were injured. And the ensuing decades have brought even more violence in schools.1

Another heartbreaking school shooting in May 2022 — this one more than 700 miles southwest of Littleton, Colorado, in the southern Texas town of Uvalde — has once again drawn the nation’s attention to violence in American schools.

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How Many School Shootings Have Happened Since Columbine?

According to the K-12 School Shooting Database, a publication of the Naval Postgraduate School’s Center for Homeland Defense and Security (CHDS), a total of 118 active shooter incidents have been reported at K-12 schools in the U.S. since 1999. These shootings are defined by the CHDS as situations where the perpetrator killed or wounded targeted or random victims within the school campus during a continuous episode of violence.

Nearly 60 percent of active shooter incidents at educational institutions since Columbine have occurred in high schools, and about 21 percent have occurred in middle or junior high schools. The remainder have happened in elementary schools, K-8 schools, and K-12 schools, according to the K-12 school shooting database.

Percentage of Active Shooter Incidents by School Level

High school 59%
Middle school, junior high, or 6-12 school 21%
Elementary school 14%
K-12 or K-8 school 3%
Other or unknown 3%

Source: K-12 School Shooting Database

School shootings and gun incidents have become so common that the news coverage of these events has fundamentally changed, with the Columbine massacre getting months of press and current events only getting a fraction of Columbine’s coverage. Some, like the Santa Fe shooting, which had ten fatalities, have gotten less attention due to the fact that other shootings, like the Parkland shooting, which had 17 fatalities, dwarf them.

How Many People Are Injured Each Year in School Shootings?

Since 1999, 440 people have been killed and 1,243 injured in shooting events at K-12 schools. This count includes all types of shooting incidents that occurred at schools or school events, including accidental discharges.

The tally of individuals injured or killed in school shootings during 2023 is more than twice as high as the number of casualties in 1999. Unfortunately, the graph shows an upward trajectory in the number of people killed or injured during these terrible events.

Calls of “never again” rang out after shootings at Sandy Hook Elementary School in Connecticut and Marjory Stoneman Douglas High School in Parkland, Florida. And yet, since the Parkland shooting in 2018 — a period of just five years — more than 200 people have died and over 550 have been injured in shootings at K-12 schools.

While many advocates and policymakers hope that these unspeakable horrors will bring about meaningful policy change, the 24 years since Columbine have illustrated the extent to which such transformation is difficult.

Columbine to Uvalde: A Tragic Timeline

Setting politics, gun rights, media blame, and coverage analyses aside, let’s look at the history of school shootings along one timeline to get a better idea of the scale of the problem.

There’s a catch to how we look at the data about school shootings. If we focus solely on major school shootings by year or on a list of school massacres with higher numbers of deaths, we miss the bigger picture. That means missing the thwarted attempts, the one-off murders, and the high frequency of smaller events between the massacres with increasingly higher death counts.

We miss situations like the school attack in East Greenbush, New York, which only resulted in one injury but had the potential to kill many more if it wasn’t thwarted. The student perpetrator has since gone on to praise both Parkland student activists and the teacher who tackled him to the ground, saying he is “a hero who I owe my life to.” That was a near-miss that could have been much worse, but those near-misses also need to be a part of the conversation about guns and schools.2

Our list of school shootings in the United States should hopefully leave an impression of just how many small events resulting in unnecessary deaths have happened with very little notice. Hopefully, the 2023-2024 school year will show a marked decline in deadly attacks in schools.

Our data

For our analysis, we relied on data from a few key sources. For data on injuries and fatalities in school shootings occurring between 1999-2022, we used records from the Center for Homeland Defense and Security (CHDS) School Shooting Safety Compendium (SSSC). Injuries and fatalities occurring in January-July 2023 were collected from the K-12 School Shooting Database (K-12 SSDB) by David Riedman. Data from this archive was used with permission. We also used the K-12 School Shooting Database to chart the number of active shooter and non-active shooter incidences at K-12 schools between 1999 and July 2023.

Our large timelines of school shootings may not align with information from the SSSC or K-12 SSDB as both include active shooter incidences at K-12 schools and universities.

  1. CNN. (2020). Columbine High School Shootings Fast Facts.

  2. Education Week. (2019). ‘I Felt More Traumatized Than Trained': Active-Shooter Drills Take Toll on Teachers.

  3. NPR. (2017). ‘Tower' Pays Tribute To A 1966 Campus Shooting That Was ‘Pushed Aside'.