Four juveniles were detained after security personnel saw them wandering the halls of Ramapo High School overnight with what appeared to be a firearm.

Franklin Lakes police, along with officers from multiple other towns and Bergen County, responded to the high school at about 1:33 a.m. Monday after school security contacted police. Security personnel told police that several individuals were walking through the school hallways, with one possibly carrying a firearm.

When officers arrived, they found four juveniles, ages 11 to 17, inside the building. According to Capt. Robert Grassi, one of the juveniles was carrying a plastic toy rifle that resembled an FN P90 firearm.

All four juveniles were taken into custody and later released to their parents or guardians.

Police later learned that the juveniles allegedly entered the building and stole a vehicle belonging to the high school. They then drove the vehicle to another high school, unlawfully entered that building and drove the stolen vehicle back to Ramapo High School.

Police have not said how the juveniles got into the schools or which towns they are from. Grassi said charges are pending and the investigation remains ongoing.