Police responded to the area of Adams Avenue and Beach Boulevard after receiving a report about the woman around 3:30 a.m. Sunday. The caller said the woman appeared to be badly beaten.
The woman was taken to the hospital and is in stable but critical condition, police said.
A person of interest has been detained for questioning, police said. Detectives said they don't believe there is a continuing threat to the community.
Anyone with information is asked to call detectives at (714) 375-5066.