A tractor-trailer drove into the path of a car, causing a fiery wreck that killed four people and badly burned another Monday afternoon, state police said.

Trooper Rob Lagoon said the tractor-trailer apparently ran a stop sign on state Route 8 and collided with the car, which was carrying five people, in Slippery Rock Township, Butler County.

The car apparently struck the tractor-trailer's fuel tank, causing both vehicles to burst into flames, state police said. Lagoon said four people in the car were killed, while the driver was able to escape the flaming wreckage.

The Butler County Coroner's Office said identification of the victims was being hampered by the fiery wreck; it was unclear when the identifications would be completed.

Retired truck driver Merlin Batykefer Sr., 71, who lives across the street from the accident, said he heard the collision and started running. When he and his son arrived, they saw the driver of the car crawl from beneath the fiery wreckage.

The badly burned driver asked about his family, who was apparently in the car with him, Batykefer said.

Batykefer said he saw state police remove four bodies from the charred wreckage.

The driver of the vehicle was taken to a Pittsburgh hospital with burns, while the truck driver had minor injuries, Lagoon said. A hospital spokeswoman declined to release details.

State police Monday night charged the truck driver, Ejub Grcic, 54, of West Valley, Utah, with homicide by vehicle and reckless driving and other traffic violations in the wreck.