Unrelated traffic accidents have killed five young people, four in the past week, in Western Pennsylvania. The victims were 18 to 20 years old.

Two of them had been riding motorcycles, at least one of them without a helmet.

Sean M. Cullen, 19, was killed in a crash at 3:54 p.m. Tuesday when a car turned into the path of his motorcycle in the 3600 block of Route 19, police said. Mr. Cullen, of Peters, had been speeding, and his helmet was strapped to his bike, Peters police Chief Harry Freucht said.

The driver of the car, Nicole Hutchins, 21, of McMurray, was treated at Canonsburg Hospital.

On the same day, Cherie D. Conaway, 18, of Penn Hills, was killed while riding a dirt bike. Details of that accident were not available yesterday.

Rachel R. Parker, 18, was killed in a crash at 4:45 p.m. Wednesday, state police said. Ms. Parker had been driving south on Route 119 in Salem when her car crossed the center line and collided with a vehicle. She was not wearing a seat belt, police said.

She was taken to Excela Health Westmoreland Hospital, where she was pronounced dead at 5:22 p.m.

Cody R. Crawford, 20, of Blairsville, who was driving the other vehicle, was hospitalized with major injuries. He also was not wearing a seat belt, police said.

Eugene G. Dozzi, 19, of Jamestown, Mercer County, died Tuesday of injuries from a June 11 accident. He was a passenger in a car that collided with a tractor-trailer in North Shenango.

The driver of the car, James A. Pashakarnis, 20, died at the scene.