Police said a police officer with his emergency lights and siren on crashed into another car Tuesday at 11:51 p.m. in Commack.
Police said the officer, whose name was not released, was taken to Stony Brook University Medical Center, where he was treated and released.
The other driver was not injured, police said.
The officer was headed south on Indian Head Road near Somers Lane when he saw a motorist speeding and he turned on his lights and siren, officials said.
Then a person driving a Subaru made a left turn in front of the cruiser. Police said the officer swerved but could not avoid the collision, according to officials.
No other details were immediately available.
No charges have been filed. Police said they are investigating.