Administrators at Potomac Senior High School called Prince William County police after the student showed a gun to a classmate in one of the bathrooms, an incident report said.
The student told the resource officer that he was using the restroom when someone showed him the weapon under the stall.
The resource office confiscated the gun while the teen was still in the bathroom. Police didn't say if it was loaded. Officers found two knives as well in the boy's bag during a search following his arrest.
Police charged the 15-year-old with three counts of possession of a weapon on school property and one count of brandishing a weapon, the report said. He was being held at Prince William County Juvenile Detention Center.
There were no injuries reported.
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