HOULTON – Mixed precipitation that fell across Aroostook County for much of Thursday caused dozens of accidents, but no serious injuries, according to police.

Sleet, snow and rain combined throughout the morning and into the afternoon made roads greasy, one state trooper said.

Route 11 was particularly slippery. Trooper Chad Fuller of the Maine State Police said that at one point Thursday morning, four tractor-trailer trucks and a school bus were stranded at the bottom of Bumpus Hill in Mount Chase because they could not get the traction to get over the hill.

Farther north at about 9 a.m., a southbound tractor-trailer loaded with wood chips had just reached the top of a hill on Route 11 about a half-mile south of the Moro-Hersey town line when the truck lost traction and began to slide backward.

Trooper Darren Foster said the truck went off the opposite side of the road where it rolled over and spilled its load.

The northbound lane was blocked until about 3:30 p.m. while the wood chips were unloaded, the trooper said.

The driver, Troy Foster, 28, of Blaine, was not injured.

The truck, a 1990 Freightliner, had about $6,000 in damage and the trailer was a total loss, Foster said.

At about the same time, another tractor-trailer jackknifed on Route 11 in Moro Plantation, about six miles north of the chip truck crash. No one was injured.

A pickup truck also slid off Route 11 and rolled over into a ditch in Hersey, just north of the Hersey-Mount Chase town line, according to Trooper Fuller.

The driver, Kevin Graham, 40, of Houlton, was not hurt.