Are 75% of guns used in school shootings found unsecured in homes? Experts say more data is needed

At an event touting the Biden administration's efforts to curb gun violence, Vice President Kamala Harris said the vast majority of guns used in school shootings come from unsecured locations in homes. 

On April 15 in Las Vegas, Harris said gun owners have a responsibility to secure firearms so children and young people can’t access them. 

"Put it in a lockbox, because especially if a young person is just curious, or, you know, wants to play with a gun … let's not make it too easy to get," Harris said. "And that's what secure storage is about. You know, the numbers that I have seen suggest that as many as 75% of school shootings resulted from a gun that was not secured."

Harris’ comments come after parents Jennifer and James Crumbley were sentenced to 10 years in prison for a deadly mass shooting their son committed in 2021 at his Michigan high school.

We took a closer look at the statistic and found the study Harris cites concluded that some school shooters acquired firearms that were considered unsecured or easily accessible in family homes — but not 75%. 

Although this is not the first time this figure has been cited.

The White House pointed PolitiFact to a 2019 U.S. Secret Service National Threat Assessment Center report on targeted school violence — planned incidents perpetrated by current or former students using weapons obtained for the specific purpose of causing others harm at school. 

The study evaluated 41 incidents, 25 involving firearms. Nineteen of the shooters, or 76%, got their guns from homes. Twelve, or 48%, of the shooters obtained their weapons from what researchers considered to be "accessible" or "not secured in a meaningful way."

"You get to the 75% or 76% number by adding the firearms from homes where the guns had been locked up," said Daniel Webster, a distinguished research scholar at the Johns Hopkins Center for Gun Violence Solutions.

Criminologists and youth gun violence experts told PolitiFact data on gun storage and its relationship to U.S. school shootings is scant. The best available figures show that many school shootings by younger perpetrators are carried out with firearms that were considered unsecured or accessible in the home.

"It makes sense that most of the guns used in school shootings come from the shooter's home. It's the easiest place for a juvenile to find a gun," said Jay Corzine, an emeritus sociology professor and a gun policy specialist at the University of Central Florida. "But, is it 75%? Is it 68%? I don't know."

The U.S. Secret Service report studied 41 incidents of "targeted school violence" that occurred at K-12 schools from 2008 to 2017.

Of the 25 shootings studied, perpetrators acquired firearms from the home of a parent or close relative in 19 cases. Some perpetrators removed the guns from locked wooden or glass cabinets, or found them locked in vehicles or hidden in closets.

Besides the 12 cases in which the shooters obtained the guns from spaces deemed unsecure, perpetrators in four incidents accessed firearms from more secured locations. Although the guns were in a locked gun safe or case, the shooters knew the combination, or where the keys were kept, or could guess the password. If those four cases are included in Harris’ "not secured" count, the percentage is closer to 64%.

In the three remaining cases, researchers could not determine whether the firearm had been secured.

The study didn’t examine school attacks involving perpetrators who researchers said couldn’t be identified, or incidents related to "gang violence, drug violence, or other incidents with a strong suggestion of a separate criminal nexus." It also didn’t include in its analysis "spontaneous acts," such as after "an unplanned fight or other sudden confrontation."  

A "unsecured" or "accessible" firearm is typically defined as one that is not safely stored in a gun safe, unloaded and separated from ammunition.

"The standard for safe and secure storage is that unauthorized or at-risk people cannot access them," said Dr. Katherine Hoops, an assistant professor of pediatric critical care who researches public health approaches to prevent firearm injury and violence.

Under that standard, Hoops said, unauthorized people "don’t have a key or the combination to the safe."

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Garen Wintemute, director of the University of California, Davis’ Violence Prevention Research Program, said "secured" means that firearms are locked up and unloaded. "‘Locked up’ doesn’t have to mean locked inside something; there can be a lock placed on the firearm," he said, with the ammunition stored in a separate location.

There is little data showing how often unsecured guns obtained from homes are being used in school shootings.

In 2019, the Wall Street Journal published an analysis of nearly three dozen mass shootings that have taken place at U.S. schools since 1990. The Journal found that 26 of 39 shooters, or about 66%, "had easy access to guns." The newspaper said "easy access" indicated that "the shooter knew where unsecured guns were in the house, had access to home gun safes or purchased the guns themselves."

One 2021 study compared shootings that occur at K-12 schools and colleges with mass shootings more broadly. 

The report defined a K-12 school shooting as one that occurs at school during the school day, involves one or more perpetrators who are current or former students, and injures or kills at least one person. Using this definition, researchers identified 57 K-12 school shootings from 2001 to 2018. 

"In our study, 46.5% of the K-12 shooters acquired the gun(s) by stealing it from a family member (often from a gun safe in the home)," Robin Kowalski, a Clemson University psychology professor and the study’s lead author, wrote to PolitiFact in an email. "Sometimes the safe was locked, sometimes unlocked. If it was locked, the shooter sometimes knew where the key was."

A January 2024 study analyzed 253 school shootings perpetrated by 262 adolescents from 1990 to 2016. It found that almost 42% of guns were obtained from relatives and that the vast majority of those firearms, nearly 96%, were stolen from family members.

Harris said that 75% of school shootings "resulted from a gun that was not secured."

Harris based her statement on one 2019 study that examined 25 school shootings. It did not find that three-quarters of guns used in those shootings came from unsecured locations.

The study found that 19 shootings were carried out with firearms taken from family homes. Of those, 12 came from unsecured or readily accessible locations, the authors said — about 48% of the shootings studied. Another four came from spaces that researchers considered "more secure" but that perpetrators were able to access because they had keys, combinations or passwords. If those are tallied in, the percentage is closer to 64%.

Experts say more robust data is needed to better understand the link between gun storage and school shootings. However, a few studies have shown that around half of these incidents are carried out with firearms obtained from unsecured or otherwise accessible locations in family homes. 

Harris’ statement contains an element of truth — the best available data suggests a relationship between unsecured guns at home and school shootings — but her statistic is off and ignores critical facts that would give a different impression. We rate it Mostly False.

RELATED: Ask PolitiFact: What does the data show on deadly shootings by 18-to-20-year-olds?