Police in Venango County said a car heading west on Route 157 in Cranberry Township veered off the road at about 6:15 p.m. Saturday.
The car then slid into the oncoming lane where it was hit by an eastbound sport utility vehicle.
Authorities said both drivers—25-year-old Taylor Knight and 52-year-old Joseph King—were pronounced dead at the scene.
Fifty-one-year-old Laura King was taken to UPMC Northwest in Seneca, where she was pronounced dead.
State police said all of the victims were from Oil City, and none were wearing seat belts. Investigators said speed was "a definite factor" in the crash.