The incident happened around 3 a.m. Sunday, Feb. 11 in Brentwood.
The 37-year-old was walking southbound on Brentwood Road at the Long Island Rail Road crossing when she was struck by a gray sedan and then a blue sedan, Suffolk County Police said.
The woman, a resident of Brentwood, was transported to South Shore University Hospital in Bay Shore for treatment of serious injuries.
Detectives are asking anyone with information on the crash to call the Suffolk County PD Third Squad at 631-854-8352 or Crime Stoppers at 1-800-220-TIPS.
Check back to Daily Voice for updates.
Click here to follow Daily Voice Brentwood and receive free news updates.