Detectives from the Street Crime Unit stopped the blue Chevy sedan at Broadway and Carroll Street around 11 p.m. Thursday, Police Director Jerry Speziale said.
The investigators had received a bulletin earlier reporting the vehicle being stolen out of Massachusetts, he said.
As they removed the driver and passenger from the vehicle, Detective John Farfan spotted the semi-automatic weapon, Speziale said.
The driver, 22-year-old Bryant C. McLaurin of Paterson, was charged with weapons offenses and receiving stolen property. A 16-year-old juvenile passenger was issued a delinquency complaint alleging the same offenses.
Police were sending the weapon to the New Jersey State Police laboratory to trace it and determine whether it had been used in other crimes.
The Chevy was returned to its owner.
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