A teenager suffered a critical skull fracture when he fell off a car hood he was riding on in the Riverton High School parking lot Friday night, police said.

"Him and his buddies decided he should ride around on the hood of a car," in the lot at 12476 S. 2700 West, said Salt Lake County sheriff's Lt. Don Hutson. He climbed on and cruised for about 50 yards until the driver, a schoolmate, slammed on the brakes about 10 p.m.

"The kid flies off and hits his head on the ground," Hutson said. "He seems somewhat OK."

But later that night, after he returned home, the teen's condition started to deteriorate, Hutson said.

His parents took him to Riverton Hospital about 2 a.m. and he was transferred to Intermountain Medical Center, where he remained in critical condition Saturday.

"A head injury, bleeding from the head, could certainly be life-threatening," Hutson said, though it doesn't look like the injury will prove fatal.

Police were investigating how many teens were involved with the hood-riding, and they could face charges, Hutson said.