Nine people were killed Friday when a tractor-trailer slammed into a line of cars stopped in traffic on an Oklahoma turnpike. (Gary Crow/Associated Press)

A tractor-trailer slammed into a line of cars stopped on a northeastern Oklahoma turnpike Friday afternoon, killing nine people, authorities said.

Oklahoma Highway Patrol Lt. George Brown said traffic was stopped on the Will Rogers Turnpike northeast of Miami because of an earlier crash when the big rig slammed into at least three cars, which then crashed into more vehicles.

"It looks like a war zone," he said. "There's mangled metal everywhere. There's debris, fluids, dead bodies."

Brown feared that rescue crews might find more bodies as they worked to get to an automobile pinned under the transport. Two of those who died were in that car, but troopers could not tell if there were more victims in the vehicle.

He said the wreckage was on a steep embankment and two tow trucks were working slowly to lift the truck up and off the car.

The truck driver was taken to an area hospital, as was a 12-year-old girl who was pinned for a time in a wrecked vehicle before emergency workers could free her, Brown said. He did not know their medical conditions.

Investigators don't believe the driver of the tractor-trailer tried to stop before the crash, Brown said. The speed limit in the area is 120 km/h.

Jodi Malphrus of Orient, Ohio, said the accident happened about 30 car lengths in front of her on the turnpike.

"It was like somebody had dropped a bomb," she said. "It was horrific."

She said the first vehicle the truck hit was an SUV, which was so mangled by the crash that it could no longer be identified as a vehicle.

Malphrus was travelling with her 17-year-old son, Jericho Malphrus, from Broken Arrow, Okla., where they toured a Bible college he may attend.

"Mainly what struck me was the amount of debris everywhere," Jericho Malphrus said. "Someone's suitcase had busted open and a little girl's clothes were everywhere."

He said a 12-year-old girl had to be removed from wreckage that had her parents' bodies in the front seat. It was not clear she was the same girl Brown referred to.

"It was disturbing," the boy said. "I'm sad for the girl."