(CNN) A teacher accidentally discharged a firearm while teaching a public safety class, injuring one student 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 lesson at Seaside High School in Seaside when he pointed his gun into the ceiling and accidentally fired it, said Abdul Pridgen, the city's police chief.

A 17-year-old student was injured by a bullet fragment or by debris that fell from the ceiling, Pridgen said.

The injuries appeared superficial, police said.

Alexander has been placed on administrative leave from his teaching job, a spokesperson with the Monterey Peninsula Unified School District said.