The vehicle restrictions imposed on the Pennsylvania Turnpike now have been extended to include all highways and expressways.

Included are Class 9 vehicles (overweight and over-dimensional trucks), large combination vehicles (tandem trailers and doubles), tractors hauling empty trailers, trailers pulled by passenger vehicles, motorcycles and recreational vehicles.

PennDOT has urged drivers of those vehicles to stop in a safe place and wait rather than moving to secondary roads, which may be impassable.

One person was killed in a chain-reaction crash involving an estimated two dozen trucks and cars this morning on snowy Interstate 80 in Clearfield County.

The eastbound lanes have been closed since the 9:30 a.m. accident and are not expected to reopen until after 8 p.m., said PennDOT spokeswoman Marla Fannin.

Neither Ms. Fannin nor state police had information about the number of people injured.

The crash occurred at mile 118 and closed the eastbound lanes from exit 111 at Penfield to exit 120 at Clearfield. Ms. Fannin said crews have cleared all remaining traffic that was backed up behind the crash scene.

With blizzard conditions in central Pennsylvania, Gov. Ed Rendell this afternoon ordered the closings of Interstates 83, 78, and part of 81, as well as I-76, I-476 and I-676 in Philadelphia area and I-176 south of Reading.

Interstate 81 is closed from the Maryland line to Interstate 80.

Mr. Rendell and Gen. Robert French, director of the Pennsylvania Emergency Management Agency, briefed reporters in a phone news conference.

They said the interstates were being closed until further notice, which could mean until sometime on Thursday, depending on when the snow and winds finally ease.

Mr. Rendell said the entrances to the highways will be barricaded, state police will instruct drivers already on the highways to get off, and electronic message boards will also tell drivers to exit the roads.

Neither official could recall when such a drastic step had been taken before.

By closing the highways in question, Mr. Rendell said, "We want to give our crews a clear shot at clearing the roads quickly.''

In Pittsburgh, trucks with snow and ice piled on their roofs are tripping sensors designed to detect overheight trucks as they approach the Squirrel Hill and Fort Pitt tunnels.

PennDOT appealed to drivers to clear the snow and ice from their vehicles before traveling. When the detectors are tripped, crews must stop traffic at the tunnel entrances to order the trucks to turn around.

On Tuesday, 73 trucks were stopped at Squirrel Hill and 17 at Fort Pitt. The snow and ice buildup also poses a safety hazard to other vehicles, PennDOT spokesman Jim Struzzi said.

The department also is urging everyone to avoid unnecessary travel.

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