Riverhead Police were called at around 4:40 p.m. Sunday, July 17, with reports of a commercial burglar alarm on Old Country Road near Osprey Avenue.
During a search of the property, police found four people near the rear of the building, police said.
One of them, a 16-year-old, was acting in a “suspicious manner” and was not compliant with officers, according to police.
Officers eventually determined that the teen had a 9mm handgun and arrested them on charges of criminal possession of a firearm, police said.
The teen was processed at the Riverhead Police Department and later released to the custody of a parent awaiting a future court date.
Police said a further investigation into the burglar alarm showed that the building had not been broken into.
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