The SUV, driven by an elderly man, rammed into people outside Farrell's Ice Cream Parlour on Friday night, Orange County Fire Authority Capt. Steve Concialdi said. The restaurant is in Buena Park, about 20 miles southeast of downtown Los Angeles.
Witnesses said the SUV lurched forward, hitting a small fence and running into those sitting and standing between the vehicle and the restaurant.
"It looked like the guy put his foot on the gas pedal instead of the brake," Daniel Long, who was eating with his family inside, told KCAL-TV. "There were three people sitting on that bench - he just went straight into them and crushed them up against the window."
Television news reports showed a silver Suzuki XL7 halfway in a parking space in front of the building, with its front end shoved over the fence onto a walkway.
A woman, 73, was critically injured and died at a hospital, authorities said.
Two other people were hospitalized with moderate injuries, three with minor injuries and a sixth person was treated at the scene for minor injuries, Concialdi said.
One of the injured was a teenage girl, police Cpl. Andy Luong said.
The SUV driver and a female passenger, both elderly, were not hurt, Luong said.
Police questioned the driver, who cooperated and was not immediately cited, Luong said.
The cause of the crash remained under investigation.
Farrell's is a chain of restaurants with decorations designed to recall century-old ice cream parlors. Servers dress in "pin-striped vests, old fashioned ties, and cane hats," according to its website.