Three children were hurt Wednesday when a police officer’s gun went off during a school safety demonstration at a school in Southern California.

The weapon was mounted on the officer’s motorcycle during the demonstration and accidentally went off at a Chino elementary school, reports the LA Times. According to KTLA, one of the students pulled the trigger on the AR-15.

The three children who were injured suffered only minor injuries when the gun went off at around 11:15 a.m. The children were not, however, injured by any gunfire, according to the New York Daily News.

The children, whose names and ages have not been released, suffered minor cuts and scrapes. Two of them were brought to a nearby hospital for treatment before being released later in the day and the third was treated at the school.

“It’s kind of strange that a gun would have been accessible, or not cleared, prior to doing the demonstration,” one student’s father, Tim Everman, told KTLA when he arrived at the school to take his son home.

Police are currently conducting an investigation along with the Chino Valley Unified School District.

“We are looking into what exactly led to the accidental discharge,” Chino police department spokeswoman Tamrin Olden said. “There are security systems in place to prevent that. That’s part of the investigation as far as how that ended up happening.”