Police responded to the intersection of Edinger Avenue and Raitt Street following reports of a woman down around 8 p.m.
The woman was found suffering from severe head injuries when she was discovered.
She had a girl believed to be around one or two years old with her. She was found with minor bumps and bruises.
Both were taken to a local hospital where the woman shortly succumbed to her injuries.
Police believe the woman was either pushed or jumped off a vehicle with the child in her arms.
A dark-colored pickup was seen leaving the scene.
The investigation was ongoing. Anyone with information regarding the incident was urged to contact Santa Ana police at (714) 245-8665.