The incident happened at about 11 p.m. Saturday on the 100 block of South Western Avenue.
Police say the driver of a red Honda Civic struck the victims, Carmen Mendoza, her daughter Sheyla Mendoza and her niece Stephanie Henriquez, who were not in a crosswalk. One victim was pronounced dead at the scene and the other two died at a hospital.
The driver and passenger stayed at the scene. They were taken to the hospital for minor injuries.
The driver was arrested on suspicion of DUI.
A memorial fund has been set up for the victims at:
Schools First Federal Credit Union
PO Box 11547
Santa Ana, CA 92711
Transit Number: 322282001
Description: Carmen, Sheyla, Stephanie MEM
Account Number: 400415614726