Napa Police responded at 6 p.m. Sunday to a report of shots fired at Rexford Mobile Estates, 1350 Pueblo Ave.
Police reported finding no gunshot victims, but five .40 caliber shell casings were located just inside the front entrance.
It appears the rounds were shot west, toward Memorial Stadium. One bullet hole was located in a power pole in front of the park, police said.
Nearby video surveillance showed the responsible vehicle is a gray Toyota Corolla, police said.
The investigation is ongoing, police said.