CLINTON TWP — A man was seriously injured Sunday afternoon when an all-terrain vehicle he was riding flipped over on top of him near an old quarry along railroad tracks, authorities said.

A medical helicopter flew the victim to a Pittsburgh trauma center following the accident shortly after 4 p.m. between Anderson and Brewer roads in Clinton Township.

State police are investigating but a report was not completed this morning. The identity of the rider, a Gibsonia-area man believed to be in his mid-30s, was not known.

The man was riding on the back of a four-wheeler designed for only a single rider when the driver attempted to travel up a hill in an area long popular with off-road enthusiasts.

“The weight of the passenger caused the vehicle to come up on them,” said Chief Chris Ballina of the Saxonburg Volunteer Fire Department. “The vehicle fell on the passenger.”

The driver, also a man in his mid-30s, apparently was not hurt.

Neither ATV rider had a cell phone, but a dirt biker riding nearby came upon the wrecked ATV and called 911.

The passenger was badly injured but conscious and talking when rescuers got there. He was bleeding from the nose and was unable to move at least some of his limbs.

A Saxonburg Ambulance crew immobilized him using a black board and cervical collar.

A LifeFlight helicopter landed several yards from the victim and flew him to Allegheny General Hospital. His condition was not known.

Buffalo Township volunteer firefighters also assisted. Rescue crews remained at the scene for a little more than an hour.