BRANCHBURG — Power remained off for approximately 1,500 customers and Route 22 was still closed to eastbound nearly four hours after an overturned truck shut down the entire highway and knocked down multiple utility poles Thursday morning, authorities said.

Route 22 was closed in both directions from about 7:30 a.m., but traffic was restored to the westbound lanes by about 11:43 a.m., Bridgewater Police said in a Nixle report.

The Raritan Valley Community College website states that the main Branchburg Campus will not open until 3 p.m. due to the power outage. The school has also cancelled Thursday's afternoon and evening concerts by Mike Aiken at the Theatre at Raritan Valley Community College.

At about 7:12 a.m. North Branch Volunteer Fire Company, Green Knoll Volunteer Fire Company, Branchburg Police and Branchburg Rescue Squad were all dispatched on the report of an overturned tractor-trailer with a trapped occupant and utility wires down at the intersection of Route 22 and Readington Road in Branchburg, according to Chief David Hickson of North Branch Fire.

Hickson said that upon his arrival on the scene, the driver of a commercial 18-yard dump truck that had come to rest on its side in the westbound lanes of Route 22 was found trapped, Hickson said.

The truck had become completely entwined in power cables. It was unclear if the power lines were still charged, Hickson said. The driver eventually self-extricated, Hickson said.

Across the highway, emergency responders had to deal with a second vehicle that had a power transformer laying across its hood, Hickson said.

The dump truck was at a construction site at Merck & Company on the westbound side of Route 22 just east of Readington Road when the driver inadvertently left the dump body raised as he exited to re-enter the highway, Hickson said.

As the truck traveled down the highway it caught the power and communication cables with enough strength to pull multiple power line poles out of the ground and snap the cables, Hickson said.

Power to the entire area including traffic signals were down, and police from adjoining communities were called in to assist with traffic, Hickson said.

According to John Anderson, spokesman for JCP&L, the utility expects power to be restored to most customers by about noon, although some larger commercial customers nearest the accident could taken longer.

Anderson said that his crews on the scene informed him that due to poles still downed in the roadway, Route 22 eastbound is expected to reman closed to traffic until at least 1 p.m.

"There will be a major amount of construction required in the area to reestablish power and communication cables," Hickson said.

Police remained on scene, while fire and rescue units cleared within about an hour of the accident, Hickson said.

Walter O'Brien may be reached at wobrien@nj.com. Follow him on Twitter @wobriensomerset. Find NJ.com on Facebook.