Panic Buttons, Classroom Locks: How Schools Have Boosted Security

Because most school shootings are carried out by current or recent students, their peers are often best positioned to notice and report a threat, said Frank Straub, director of the Center for Targeted Violence Prevention at the National Policing Institute, who studies averted school shootings.

“Many of these people engage in what’s called leakage —they post online, they’ll tell a friend,” Mr. Straub said. He added that teachers, parents and others should also look out for signs: a child becoming withdrawn and depressed, a student drawing doodles of guns in a notebook.

“Fundamentally, we have to do a better job of recognizing K-12 students that are struggling,” he said. “And that’s expensive. It’s very difficult to prove what you prevented.”

Most school shootings, though, are not planned, mass attacks.

“The most common occurrence — throughout history and throughout the last couple of years as things have dramatically increased — is there are fights that escalate into shootings,” said Mr. Riedman of the K-12 School Shooting Database. He pointed to national upticks in shootings, and said the data suggests that there are simply more people, even adults, bringing guns to school campuses.

Christi Barrett, the superintendent of Hemet Unified School District in Southern California, knows that no matter what she does, she cannot fully eliminate the possibility of risk for each of the 22,000 students and hundreds of employees in her sprawling district, which spans 28 schools and nearly 700 square miles.

But she has worked to be proactive, starting several years ago with a locked door policy for every classroom.

The district is also in the midst of transitioning to electronic door locks, which she hopes will reduce any “human variable” or fumbling with keys in a crisis. “If there is an intruder, an active shooter, we have the ability to lock down everything instantaneously,” she said.