An active-shooter training in Indiana took a gruesome turn earlier this year when sheriff’s deputies shot elementary school teachers in the back with plastic pellets, mock-execution style. The teachers union detailed the incident this week, highlighting the extreme and potentially ineffective measures many schools have undertaken to avert future mass shootings.

Local law enforcement carried out the drill with the teachers of Meadowlawn Elementary School in Monticello, Indiana, in January, the Indiana State Teachers Association said in a meeting with state legislators on Wednesday. The drill involved dividing the teachers into small groups and instructing them to face a classroom wall and kneel. Then, deputies with the White County Sheriff’s Office fired plastic pellets into the backs of more than 20 teachers without warning. Several teachers were injured, a representative for the district’s union said, though none have publicly come forward about the incident.

The teachers union detailed on Twitter how teachers heard their colleagues scream from getting shot.

“The teachers were terrified, but were told not to tell anyone what happened,” the union tweeted. “Teachers waiting outside that heard the screaming were brought into the room four at a time and the shooting process was repeated.”

During active shooter drill, four teachers at a time were taken into a room, told to crouch down and were shot execution style with some sort of projectiles - resulting in injuries to the extent that welts appeared, and blood was drawn. — Indiana State Teachers Association (@ISTAmembers) March 20, 2019

The Indiana State Teachers Association were meeting with state legislators to lobby them to amend a pending school-safety bill to prohibit active-shooter drill instructors from firing projectiles at teachers.

The bill was inspired in part by the 2018 shooting at the Marjory Stoneman Douglas High School in Florida, during which a gunman killed 17 students. That shooting helped galvanize a movement to address an alarming new data point: Although school shootings remain relatively uncommon in the US, last year saw the largest spike in school shootings since Columbine, according to an analysis by the Washington Post.

Active-shooter drills are becoming more common, but do they actually work?

Active-shooter drills are now the new normal for students across the US as lawmakers and school administrators continue to wrestle with how to make public schools safer environments. As of 2018, more than 187,000 students at 193 schools experienced a school shooting since Columbine, according to the Washington Post. While those shootings have caused only 375 deaths or injuries, the threat of such violence has helped fuel an entire industry of campus security companies and products. States are now requiring schools to bring active-shooter drills into every classroom. Vox’s Alexia Fernández Campbell detailed the scope of pending school safety laws last year:

Since Columbine, 32 states have passed laws requiring schools to conduct lockdown drills or some form of emergency drill to keep students safe from intruders. Some states went even further after 20 children died in Newtown, Connecticut, in 2012. Now, six states require specific “active shooter” drills each year. That means the training must be specifically tailored to respond to an armed gunman out to kill. There is no consensus on what these drills should look like, but several states, including Missouri, require shooting simulations with police officers. In the 2003-04 school year, when the National Center for Education Statistics began collecting this data, 46.5 percent of all public schools had conducted active shooter drills with students. By 2013-14, a year after Sandy Hook, that figure had climbed to 70.3 percent. In the most recent data, for 2015-16, “lockdown drills” — a broader category that NCES used for that year’s survey — were being conducted in 94.6 percent of schools.

This new era of school-safety measures is having a sweeping impact on millions of children. The Washington Post did an exhaustive survey of the 2017-2018 school year and found that more than 4.1 million students experienced at least one lockdown drill — 220,000 of those were kindergarten or preschool-age students, the Post found.

There is limited evidence pointing to whether these drills are at all effective, but students are increasingly reporting feeling traumatized by the prospect of terror and violence in their classrooms. The National Association of School Psychologists found that “depending on circumstances, some lockdowns may produce anxiety, stress, and traumatic symptoms in some students or staff, as well as loss of instructional time.”

Lockdown drills have other limitations, too. As Campbell reported last year, the annual lockdown drills Marjory Stoneman Douglas High School had been holding for more than a decade weren’t enough to stop a shooter. In fact, the shooter was an expelled student who had likely been through those lockdown drills himself.

The disconnect between training and prevention has inspired a range of new approaches toward averting the next school shooting. As Indiana teachers argued this week, however, shooting teachers with rubber bullets shouldn’t be one of them.