LOS ANGELES (AP) — School police departments across the country have taken advantage of free military surplus gear, stocking up on mine resistant armored vehicles, grenade launchers and scores of M16 rifles.

At least 26 school districts have participated in the Pentagon’s surplus program, which is not new but has come under scrutiny after police responded to protesters in Ferguson, Missouri, last month with tear gas, armored military trucks and riot gear.

Now, amid that increased criticism, several school districts say they’ll give some of the equipment back, while others plan to keep the rifles they received. Nearly two dozen education and civil liberties groups sent a letter earlier this week to the Pentagon and the Justice and Education departments urging a stop to transfers of military weapons to school police.

The Los Angeles Unified School District — the nation’s second largest school district covering 710 square miles and enrolling more than 900,000 students — said it would remove three grenade launchers it had acquired because they “are not essential life-saving items within the scope, duties and mission” of the district’s police force.

But the district plans to keep the 60 M16s and a military vehicle — known as an MRAP — used in Iraq and Afghanistan that was built to withstand mine blasts.

District police Chief Steve Zipperman told The Associated Press that the M16s are used for training, and the MRAP, which is parked off campus, was acquired because the district could not afford to buy armored vehicles that might be used to protect officers and help students in a school shooting.

“That vehicle is used in very extraordinary circumstances involving a life-saving situation for an armed threat,” Zipperman said. “Quite frankly I hope we never have to deploy it.”

Law enforcement agencies around the country equipped themselves during learner budget years by turning to the Pentagon program, which the Defense Department has used to get rid of gear it no longer needs. Since the Columbine school shooting in 1999, school districts increasingly participated.

Federal records show schools in Florida, Georgia, Kansas, Michigan, Nevada, Texas and Utah obtained surplus military gear. At least six California districts have received equipment, state records show.

U.S. Rep. Adam Schiff, D-Calif., said while there’s a role for surplus equipment going to local police departments, “it’s difficult to see what scenario would require a grenade launcher or a mine resistant vehicle for a school police department.”

In Texas, Tina Veal-Gooch, executive director of public relations at Texarkana ISD, said the 2012 school shooting in Newton, Connecticut, led the district to acquire assault rifles. The district has no plans to return the weapons.

In Florida, Rick Stelljes, the chief of Pinellas County schools police, said Wednesday that the county has 28 semi-automatic M16 rifles. They have never been used, and he hopes they are never needed.

But, he said, they are “something we need given the current situation we face in our nation. This is about preparing for the worst-case scenario.”

School officials in Utah’s Granite School District and Nevada’s Washoe County School District, encompassing Reno, also said they don’t have any immediate plans to give back the M16s they received.

San Diego Unified School District is painting its MRAP white and hoping to use the Red Cross symbol on it to assuage community worries, said Ursula Kroemer, a district spokeswoman. The MRAP has been stripped of weapon mounts and turrets and will be outfitted with medical supplies and teddy bears for use in emergencies to evacuate students and staff, she said.

Jill Poe, police chief in the Southern California’s Baldwin Park school district, said she’ll be returning the three M16 rifles acquired under her predecessor.

“Honestly, I could not tell you why we acquired those,” Poe said. “They have never been used in the field and they will never been used in the field.”