in Orange County were detained on Monday after police found a semi-automatic handgun and ammunition in their backpacks.

Officers from the Fountain Valley Police Department responded to the school after receiving a report that a student possibly had possession of a firearm.

Three sixth-grade students were detained after police searched their belongings and found a semi-automatic handgun and ammunition in their backpacks, police said.

A preliminary investigation by police indicated that it was not an active shooter incident. They believe it was an isolated event and they deemed there was no ongoing threat to campus safety.

Officers remained on campus out of an abundance of caution and maintained an increased presence at school for several days after.

It is unclear if any of the students were arrested or released to their parents.

CBS News Los Angeles reached out to Fountain Valley police and the Ocean View School District for an update on the incident.