The crash happened in Huntington Station at 7:10 p.m. on Thursday, Dec. 29.
A woman was trying to cross New York Avenue near the Huntington Public Library when she was hit by the car that left the scene by traveling south, authorities said.
The woman was airlifted to Stony Brook University Hospital.
Authorities said the car is an older model gray four-door sedan, and it might be a Nissan Sentra or Altima.
Suffolk County Crime Stoppers is offering a cash reward for information that leads to an arrest.
Tips can be submitted by calling 1-800-220-TIPS.
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