DENVER - Thousands of travelers heading to ski areas for the holiday weekend were stalled by giant traffic jams Saturday as highways were blocked by crews removing snow slides.

One avalanche at Berthoud Pass on Highway 40, the main road to the Winter Park ski resort, knocked a state maintenance vehicle off the road during the night, said Colorado Department of Transportation spokeswoman Stacey Stegman.

That pass was the scene of an avalanche last month that knocked two vehicles off the road and stranded several motorists. No injuries were reported because of snow slides or avalanche mitigation.

Elsewhere, avalanche crews firing explosive charges to break up potential avalanches dislodged a massive slide that buried Interstate 70, the main access from Denver and the urban Front Range corridor to many of the state's major ski resorts, including Vail and Aspen.

"We've just gotten so much snow up there in the last two days," Stegman said. "This is one of the biggest ski weekends of the year. We would love to keep the highway open. It's just so much snow."

By the time officials reopened I-70 shortly after 10 a.m., the traffic jam stretched east for 10 miles, Stegman said.

The storm, which had moved out of the state Saturday, piled up as much as 18 inches of snow in the mountains, Stegman said.

The storm also blasted the metropolitan area with wind as high as 100 mph.

At Denver International Airport, officials were still "baffled" Saturday by cracks that formed during the storm in the windshields of 12 airliners, airport spokesman Steve Snyder said.

Investigators had found no evidence of wind-blown debris that could have caused the cracks, which delayed some flights, Snyder said.

No emergencies were declared and no injuries were reported.

Windshields on two Frontier airliners were cracked while they were airborne near Denver, and two others were cracked while the planes were on the ground, said Joe Hodas, spokesman for Denver-based Frontier Airlines.

Airplane windshields are heavily reinforced, designed to handle travel at hundreds of miles per hour and even survive collisions with birds, Hodas said.

"It's truly bizarre," he said.

SkyWest Airlines reported cracked windshields on eight planes that were taking off or landing Friday, spokeswoman Marissa Snow said. One plane's windshield cracked while it was airborne.

Elsewhere, a twin-engine Cessna crashed during a snowstorm southeast of the airport at Council Bluffs, Iowa, killing at least three people late Friday, officials said.

The cause of the crash was not yet known. The National Weather Service said a fast-moving storm was pushing through the area with snow, wind gusting up to 53 mph and poor visibility.

In Pennsylvania, the last of hundreds of motorists stranded on a 50-mile stretch of Interstate 78 were freed Friday, and three major highways reopened Saturday. Posted speed limits were reduced to 45 miles per hour until authorities deem it safe to drive at regular speeds.

Pennsylvania Gov. Ed Rendell apologized for the state's "totally unacceptable" handling of the storm and the I-78 tie-up, where some motorists were stranded for as long as 24 hours. He blamed an "almost total breakdown in communication" among state agencies.

At least 24 deaths were blamed on the storm system and accompanying cold: six in Ohio; three in Nebraska; two each in Illinois, Indiana, New York, New Jersey and Delaware; and one each in Missouri, Pennsylvania, Virginia, New Hampshire and Louisiana.