The incident began when the window of a cell phone store on Merrick Road in Amityville was shattered by a bullet, police said.
Seconds later, a person saw cars racing north of the location and heard additional shots fired.
Police say the witness called 911 and a 30-year-old man was found on Homestead Avenue, near Orchard Street, with gunshot wounds to the head.
A person running from the scene was briefly detained and released.
The victim is in critical condition with life-threatening injuries. He has not yet been identified.
Investigators believe the victim was the intended target and was not a resident of the neighborhood.
Police are investigating whether the shooting was drug or gang-related.
Schools in the area were put on lockout but it was lifted at 3:45 p.m. and students were dismissed.
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