The incident happened in Deer Park at about 8:30 p.m. on Sunday, Oct. 30, according to the Suffolk County Police Department.
SCPD said a 17-year-old Deer Park boy was standing on the running board while holding onto the roof rack of a 2014 Jeep Grand Cherokee that his friend was driving south on West 4th Street, between Grand Boulevard and Park Avenue.
The boy fell off of the vehicle and hit his head on the pavement, police said.
He was taken to a hospital to be treated for serious, non-life-threatening injuries, authorities said.
SCPD said the 17-year-old Deer Park resident who was driving the Jeep was not injured.
Authorities asked anyone with information about the incident to call police at 631-854-8152.
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