Medics were dispatched to the 800 block of Old Eagle School Road near Wallace Drive shortly before 10:00 pm.
Investigators say the driver of a 2002 Saturn improperly passed a 1999 Volvo and lost control. The Saturn sideswiped the Volvo, lost control, and hit a utility pole.
Three people inside the Saturn were seriously hurt. One of the victims was flown to the Hospital of the University of Pennsylvania, while the other two were taken by ambulance.
Three people inside the Volvo were evaluated at the scene.
Police say it appears that the drivers of both the Saturn and the Volvo knew each other.
Anyone with any further information is asked to call the Tredyffrin Township Police Department at 610-644-3221.
