SLIPPERY ROCK TWP., Pa. - Nine vehicles including a transit bus were involved in a chain reaction crash that shut down Route 422 in Lawrence County's Slippery Rock Township overnight and injured seven people, three of them seriously.

State Police say a tractor-trailer being driven by 63-year-old James McKinley of Dilltown, Pennsylvania crashed into the back of a pickup truck that had stopped for a red light at State Route 388 shortly before 5 pm Wednesday.

The pickup truck was pushed into the SUV in front of it. The chain reaction continued with the SUV ramming four other vehicles at the red light, including a New Castle Area Transit Authority bus carrying the driver and sixteen passengers.

After striking the pickup truck, police say the tractor-trailer crashed into a parked tractor-trailer.

Three people from New Castle were flown by medical helicopter to Mercy Health in Youngstown with major life-threatening injuries including the driver of the pickup truck, 26-year-old Brandon Vanscoy, the driver of the SUV, 67-year-old Deborah Martell, and her passenger, 54-year-old Maura Criscito.

As of 5 am Thursday there is no word on the conditions of the three seriously injured people.

The driver of the tractor-trailer and two passengers on the bus were taken to UPMC Jameson for treatment of minor injuries.

The driver of another pickup truck damaged in the crash also suffered minor injuries according to the police report.

Police are looking for another Ford F-150 pickup truck that drove away from the crash.

The accident remains under investigation.