Six teenagers in a stolen car slammed into a freight train parked at a railroad crossing early Thursday, killing four of them and leaving another in critical condition, authorities said.

The impact tore the roof off their Jeep Cherokee as it skidded under a tanker before winding up on the other side of the tracks, said Lt. John Martin, a spokesman for the Harris County Sheriff's Department.

Authorities believe the 15-year-old driver didn't see the train until it was too late. The intersection was dark and didn't have a crossing gate or lights.

Three 14-year-olds and a 13-year-old, all seated in the back, were killed. The driver and a 15-year-old in the front passenger seat were airlifted to a Houston hospital, where the driver was in critical condition and the other was listed as stable.

"There were some short skid marks," Martin said. "It would appear the driver noticed the train immediately before impact, but not early enough to stop hitting the train."

The car was reported stolen shortly before the accident and did not belong to any family members of the passengers, Martin said. At least two of the victims were cousins, he said.

No identities were immediately released.