A witness said the woman went into Jerry's Liquor store in the 500-block of East Sixth Street and was asked to leave, but she began to break things, including a store window.
The man, who apparently works at the store, grabbed a bat, chased the woman outside and began hitting her a number of times as she screamed.
The witness said the woman is apparently known in the neighborhood for breaking the windows of local businesses and has a mental illness.
Corona police arrived after the beating and took the woman into custody, according to the witness. She was later treated for her injuries at a hospital. Her condition was not immediately known.
On Thursday, police returned to the scene and took the man into custody.