San Clemente High School was evacuated on the first day of school Wednesday after a bomb threat made in note was found at Camp Pendleton.

According to the Orange County Sheriff's Department, a naval officer from Camp Pendleton was reported missing, and when officials checked his barracks, they found a note indicating he had, or was going to, place explosives at the school.

Sheriff's Department spokesman Jim Amormino said the naval officer, identified as 22-year-old Daniel Morgan, has not been located yet. Morgan is white, wears glasses, and has short hair. He owns a white Jeep Wrangler with a black top and 35-inch tires, with license number 6NKZ930.

About 3,200 students and 180 staff members were evacuated bout 8:45 a.m. and initially taken to the school stadium after authorities deemed the stadium safe. But because of the hot weather conditions, authorities moved everyone into the gym. One student was treated for heat exhaustion.

Just before 1 p.m., students were being released, with freshmen first. It was unclear how long the process would take. Students without cars were being directed to a nearby Albertsons parking lot.

Sheriff's deputies were conducting a room-by-room search of the campus.

"At this stage, we don't know where the possible explosive devices are. They could be anywhere on the exterior or interior of the high school," Amormino said.

Parents and other community members were asked not to go to the school at this time. Parents can call the school district at (949) 234-5575, or (949) 234-5583 for Spanish.

Source: KABC-TV/DT