ORO GRANDE, Calif. (KABC) -- A teacher at a middle school in San Bernardino County was arrested for allegedly taking inappropriate photos of students.San Bernardino County Sheriff's Department officials said a student at Riverside Preparatory Middle School in Oro Grande approached a school administrator on Friday and reported observing 27-year-old John Martin Sheldon taking a photo or video of a student under a desk.An investigation turned up a similar incident in February involving Sheldon taking inappropriate photographs of female students during school hours.Several minors were interviewed regarding the allegation of inappropriate conduct after school administrators reported it to the Victor Valley Station.Sheldon was arrested for annoying or molesting a child under the age of 18 and invasion of privacy. He was booked at High Desert Detention Center in Adelanto.Sheldon is employed with the Oro Grande Unified School District as a teacher at Riverside Preparatory.Detectives believe there may be more victims. Anyone with information is urged to contact the Specialized Investigation Division, Crimes Against Children Detail, Detective Lisa Guerra (909) 387-3615. Callers wishing to remain anonymous are urged to call the We-Tip Hotline at 1-800-78-CRIME (27463).