A Timeline of School Shootings Since Columbine

• Since 2015, school shooting incidents in the U.S. have skyrocketed compared to previous decades.
• There were 233 shooting incidents at K-12 schools in 2025, resulting in 221 injuries and fatalities. This is down from the high of 352 incidents in 2023.
• Between 1999 and 2025, there have been an average of 6 active shooter events in K-12 schools per year.
• The majority of active shooter incidents since 1999 have happened in high schools – 55 percent to date, to be exact.

In 2024, President Joe Biden gave a speech to mark the 25th anniversary of the Columbine massacre. In that speech, he said more than 400 school shootings have taken place since Columbine, exposing more than 370,000 US students to gun violence.1 Given our focus on keeping people safe, we have charted the frequency and severity of school shootings in the timeline.

Click the image to view the full-size visualization

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.

From the Sandy Hook shooting in 2012 to the Uvalde shooting in 2022 to the school shooting we all know is coming in the near future, gun violence in American schools continues year after year. As security experts, we want to better understand these tragedies, so we’ve been maintaining an up-to-date timeline of school shootings.

How Many School Shootings Have Happened Since Columbine?

According to the K-12 School Shooting Database, a total of 154 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.

Fifty-five percent of active shooter incidents at educational institutions since Columbine have occurred in high schools, and about 22 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

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, 796 people have been killed and 1,740 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 2025 is more than twice as high as the number of casualties in 1999, though the total number of victims in 2025 was lower than the all-time high in 2023. Overall, 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, more than 450 people have died and over 1,100 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 26 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 2026 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 at K-12 schools occurring between 1999-2025, we used records from the K-12 School Shooting Database (K-12 SSDB) compiled by David Riedman. Data from this archive was used with permission. Data on shootings occurring at college and university campuses came from Mother Jones data, US Mass Shootings, 1982–2025 and The Violence Project Mass Shooter Database.