There's no word on how the woman got control of the LBPD vehicle.
A man who works at a deli adjacent to the gas station said the woman pulled into the gas station, left the patrol car parked next to a pump and went inside the eatery.
She then asked the clerk for matches, to which he replied they had none. When the woman asked for a lighter, he told her it would cost her a dollar, the clerk said.
The woman told him she had no money, left the deli and began rummaging through the police car, adding that he immediately called police.
The woman apparently couldn't get the car started again.
A man who called 911 says the dispatcher told him she had no idea there was a car missing.
The L.A. officers didn't know either and just thought it was unusual to see a Long Beach vehicle in their area.
The woman, who is believed to be mentally ill, was taken into custody by LAPD officers, but no decision was immediately taken on whether she would be booked in Los Angeles or handed over to Long Beach police, authorities said.
An AR-15 rifle, still secured, could be seen inside the Long Beach police cruiser.
Long Beach police were summoned to the location shortly after the car was recovered.
City News Service contributed to this story.