The victim's identity is being withheld pending notification of her family.
A Toyota 4Runner going south on Harbor Boulevard struck the victim, who was crossing Harbor Boulevard.
The 4Runner, driven by 52-year-old Irvine resident Fern Eisler, was then hit from behind by a Toyota Corolla, driven by 20-year-old Irvine resident Neal Eisler.
Both drivers are participating with police in the investigation.
Anyone who may have witnessed or has information regarding this traffic collision is asked to contact Costa Mesa Police Department investigator Rick Cummings at (714) 754-5264.
City News Service contributed to this report.