A bus driver whose Greyhound veered off the Pennsylvania Turnpike and smashed into a parked tractor-trailer was sober and apparently healthy before the accident, an autopsy found.

The driver, Milton S. Wisner, his wife and an 8-year-old boy they had helped raise were among seven people killed Saturday in the crash that happened as Wisner was making his final run before retiring."We know he didn't have a stroke, at least no signs of a stroke or a tumor. We could see no heart blockages or anything acute which could indicate a heart attack," said Huntingdon County Coroner Dan Quarry, who witnessed the autopsy. "We also know that he was not intoxicated."

Wisner, 61, of Boothwyn, Pa., died of "massive crushing type trauma to his entire body," Quarry said Monday.

So far, investigators have found no signs of mechanical failure in any part of the bus, State Police Lt. Richard Kovalik said. There were no skid marks to indicate that Wisner had applied the brakes nor any sign he'd fallen asleep at the wheel.

Quarry said it was possible that Wisner became distracted or had trouble with the rainy weather.