(CNN)

— A teacher accidentally discharged a firearm while teaching a public safety class, injuring three students at a Northern California school on Tuesday, police said.

Dennis Alexander, who is Seaside City’s mayor pro tem and a reserve officer with the Sand City Police Department, was teaching a gun safety lesson for his administration of justice class at Seaside High School in Seaside, California when he pointed his gun into the ceiling and accidentally fired it, said Abdul Pridgen, the city’s police chief.

Three students were injured by debris, including a 17-year-old who sustained moderate injuries when bullet fragments lodged in his neck.

The student’s injuries appeared superficial and were not life threatening, police said.