The accident occurred just after 3 p.m. on Route 926/Street Road near the intersection with School House Road in East Marlborough Township, troopers said in a release.
Investigators believe a car was turning right from School House Road onto Street Road but "failed to properly clear the stop sign" and struck an eastbound vehicle on Street Road.
When state police arrived, the eastbound car was resting on its roof, while a passenger from the turning car had been ejected from the vehicle. That victim, a 17-year-old Chadds Ford resident, was pronounced dead at the scene, troopers said.
Authorities did not describe the conditions of the two drivers but said one of them is suspected to have been operating under the influence. The name of the victim was not released.
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