The driver of the car, Unique Bishop, 21, fled after Monday afternoon's fight but later turned herself in to authorities and was booked for investigation of murder, police said. She was being held on $1 million (€690,000) bail.
"It was totally an intentional act to kill the woman. It was the driver's way of settling the dispute. It was a horrific act," said LAPD Deputy Chief Charlie Beck.
It was not immediately known if Bishop had obtained an attorney.
Police said the cause of the dispute is unclear, but was part of a planned confrontation between two groups of women in their early 20s. Witnesses told police they saw women shouting at each other and fighting at a discount store parking lot. The fight then moved onto the street and into a gas station.
Dozens gathered at the gas station and watched as Bishop got into her car and drove it into the group. One of the victims was pinned against another car, police said.
The woman killed was eight months pregnant and another victim was in critical condition and expected to lose her leg, authorities said. None of the victims' identities were released.
"We have seen women around gangs before, but we haven't seen anything like this event before," said police Cmdr. Pat Gannon.