The crash happened on I-95 southbound in Port Chester at about 8:45 p.m. on Thursday, Sept. 8, New York State Police said.
A marked State Police car was parked on the shoulder of the highway between Exits 16 and 17, and a trooper was walking back to the car after removing debris from the roadway when an unknown vehicle struck them, authorities said.
The vehicle did not stop and continued traveling south, police said.
Police said the trooper was taken to the hospital for treatment of multiple injuries and has since been released to recover at home.
Authorities asked anyone with information about the crash to call the Crime Stoppers Hotline at 1-866-313-TIPS.
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