It happened just before 4 a.m. Sunday along Route 202 and Baltimore Pike.
Pennsylvania state police say two teens were in a vehicle that had struck a pole and flipped over.
The 17-year-old girl killed was a passenger in the vehicle.
The driver, a 19-year-old man, was taken to the hospital with life-threatening injuries.
The names of the victims have not been released.
An investigation into the cause of this crash continues.