Napa Police responded to a report Sunday night of an intoxicated man with a gun who was allegedly showing drugs to someone in the parking lot of Oxbow Public Market, 610 First St.
When officers arrived, they stopped the vehicle, which had moved to a parking lot on McKinstry Street, and arrested both occupants, police said.
Drugs were in plain view, police said, adding that a search of the vehicle revealed more than 200 additional prescription-strength pills and a loaded stolen pistol.
Police arrested Federico Audelo, 34, a convicted felon, for investigation of possession for sale of a controlled substance, possession of a firearm while in possession of a controlled substance, possession of a firearm by a prohibited person, carrying a loaded firearm in public, carrying a loaded stolen firearm, and possession of a firearm by an addict.
Audelo was released from the Napa County jail after posting $50,000 bail.
The driver, Satrina Marie Linehan, 45, was arrested for investigation of driving while intoxicated.