CRANBERRY TWP - Township police are seeking the unknown driver in a hit-and-run crash Monday night that seriously injured a motorcyclist at Rochester Road and Chadborne Court.

George Ballas, 40, of Freedom, Beaver County, was flown by medical helicopter with potentially life-threatening injuries to an unknown Pittsburgh hospital following the collision about 8:55 p.m., authorities said.

Ballas, who was not wearing a helmet, was unconscious and bleeding when paramedics arrived and found him lying on the road.

Deanne Robison, no age given, of Sewickley, Allegheny County, a passenger on the motorcycle, suffered only minor injuries, according to police. She also was not wearing a helmet.

Police said the motorcycle was traveling west on Rochester Road when a car northbound on Chadborne Court made a left turn and pulled into the path of the bike.

The driver of the car did not stop following the collision. The vehicle was last seen traveling west on Rochester Road.

Witnesses described the car as tan or brown, possibly a Dodge K-car model with a square back. No other description of the car was available; witnesses believed the driver was a man "but we're not certain of that," said Cranberry Township Police Lt. Jeff Schueler.

Police immediately issued a "be on the lookout" advisory for the unidentified car, which was believed to have sustained rear and passenger side damage in the crash.

Anyone with information about the crash is asked to call Cranberry Township police at 724-776-5180.

The road was closed for at least two hours after the collision as police accident reconstruction specialists investigated.