CANANDAIGUA, N.Y. (AP) – A charter bus that swerved off a highway and rammed a parked tractor-trailer, killing four people and injuring 19, left no skid marks before the collision and had no obvious mechanical problems, state police said Monday.

The Coach Canada bus, which rammed into the rig so hard that it split in half lengthwise, was equipped with a “black box” device that might help reveal what caused the wreck.

“We’ll never be able to prove one way or another whether his eyes are open or closed,” Frost said. “But if he’s attentive to what he’s doing, it will give us signals. If he’s distracted, that would fall under the same criteria as someone falling asleep. We’re going to see the same indicators on the highway.”

Investigators declined to estimate how long it would take to analyze the data.

The bus was unable to travel faster than 68 miles an hour, which was just 3 mph over the speed limit on a stretch of Interstate 390 near Geneseo in western New York where the crash happened at around dusk Saturday, said Erie Coach Lines, a Canadian company that owns the bus.

Three people traveling with a women’s hockey team from Canada and the driver of the tractor-trailer were killed when the bus swerved into the back of the truck, which was parked on the side of the highway.

Seven of the 19 injured were discharged Monday from a hospital in Rochester, leaving four still hospitalized – three passengers in guarded condition and the bus driver, who was satisfactory.

Visibility at the time of the crash was good and the highway was dry and clear, state police Maj. Steven White said. Driver Ryan Comfort, of Ontario province, told police he hit something in the road before the crash, White said.

“We did not find a blown tire,” said Frost, who works for the state police accident reconstruction unit. “We did find the front right tire was damaged as a result of the collision but we haven’t found anything that would indicate any pre-impact problems.”

Because the bus has an air-braking system, he added, “you may not see skid marks, especially if he reacts real close to the hazard that he hit.”

Comfort has not been charged and “we’re not saying that he can’t leave,” White said.

The National Transportation Safety Board sent a three-member team to investigate.

The bus was chartered by the Windsor Wildcats, a club hockey team of women ages 18 to 21. After a morning game in Rochester, the team was taking some players, family members and coaches to a ski center when the crash occurred 27 miles south of Rochester.

The driver of the tractor-trailer, owned by Xtra Lease Inc. of Mechanicsburg, Pa., had parked it on the shoulder and was outside the cab when the bus rear-ended the rig, police said.

Ernest Dale Zeiset, 42, of Womelsdorf, Pa., was killed along with three bus passengers – team coach Richard Edwards, 46, and his 13-year-old son, Brian, from LaSalle, Ontario, and Catherine Roach, 50, of Windsor, Ontario, the mother of a player.

AP-ES-01-31-05 1728EST