Eighteen.

That’s the number repeated across airwaves and on websites after Wednesday’s deadly Florida school shooting, as it was called the 18th one in the United States in 2018.

That statistic lumped the Parkland, Fla., incident, where a student armed with an AR-15 killed 17 people, with one Minnesota incident. On Feb. 5, a third-grader pushed the trigger on a Maplewood officer’s holstered gun, striking the floor. No one was hurt.

“This incident at Harmony [Learning Center] shouldn’t be counted as a school shooting,” Maplewood Police Cmdr. Dave Kvam said Thursday, adding that school shootings should be defined as deadly, intentional criminal acts. “It’s misleading … and probably leads people to believe the issue is greater than it is.”

The role of guns in America is hotly debated, but school shootings data vary based on wide-ranging definitions.

The statistic about the 18 shootings came from Everytown for Gun Safety, a New York City nonprofit that aims to reduce gun violence.

“Every time gunfire breaks out on school grounds, it can shatter a child’s sense that they are safe in their school and in their community,” Sarah Tofte Everytown’s director of research, said in a written statement.

The number quickly made headlines.

As a Washington Post analysis pointed out, the number depends on what is defined as a “school shooting.” While Everytown included any discharge of a firearm at a school — including accidents — that isn’t everyone’s definition.

“That number is not wrong, but connecting that with what happened in Florida is wrong,” said Jillian Peterson, assistant professor of criminology and criminal justice at Hamline University.

“If you’re talking about gun violence in general, that 18 can be important and powerful,” she said. But when talking about deadly mass school shootings like Florida’s, “that headline seems to be conflating the two.”

She and James Densley, an associate professor of criminal justice at Metropolitan State University, are building a database of mass shootings, using the FBI’s definition of four or more victims killed, excluding gang violence. They’ve tracked 135 U.S. mass shootings from 1966 to 2017, and include the Parkland, Fla., incident as the first mass school shooting of 2018.

Education Week started its own school shootings database, counting six in the United States in 2018. It defines one as a discharge of a firearm in a K-12 building or facility, on a school bus, or at a school-sponsored event, injuring or killing people.

“You hear the term ‘school shooting’ and your brain automatically assumes Columbine, Sandy Hook or this more recent shooting,” Densely said. “But there are lots of incidents where one person was shot and killed.”

With varying definitions by advocacy groups, he said there needs to be a neutral source for school shootings.

“There needs to be a greater consensus about what constitutes a school shooting,” he said. “But of course, one incident is too many.”