Cellphone videos show Long Beach police pulling a woman to the ground and beating her with a baton after a fight outside a bar.
Ashleigh Sola, 25, said the officers detained her for unknown reasons and used excessive force, leaving her bruised and in pain, KTLA reported.
"I just remember being dragged to the floor," the Long Beach resident told KTLA.
But police said the force was necessary.
"In order to protect the safety of the victim, officers used force to arrest the violators," said Sgt. Megan Zabel, Long Beach police spokeswoman. "Although it appears video was captured by bystanders, nobody has come forward with such video at this time."
The drama unfolded when officers were patrolling in the 200 block of Pine Avenue about 2 a.m. and saw two men fighting in the street.
Officers tried to stop the fight and detained two people. The main aggressor in the fight, they said, appeared to be intoxicated. Officers tried to arrest him but several people intervened.
Police arrested Sola; Thomas Ramirez, 35, of Wilmington; and Gerardo Lopez, 26, of Paramount. Police say Sola and the two men suffered minor injuries and were taken to a hospital.
Kevin Grant, 39, of Long Beach, also was arrested because police said he refused to leave the area when ordered by officers.
Police said they are conducting an internal review of the incident "to ensure the arrests were made within the law and within department policy."