Deputies took 19-year-old Brandon Lee Williams into custody. He was charged with possession of a weapon on school grounds.
The sheriff's office said it was notified of a person at Grays Creek High School in the parking lot with a gun. Deputies checked the parking lot and found a red GMC that had an empty holster on the dashboard.
Deputies asked the occupants to get out so they could safely search the vehicle. Deputies found a handgun in the backseat floorboard.
Williams is being processed into the Cumberland County Detention Center.
Williams will have a first court appearance Friday.