Snowfall delayed repairs Friday to a section of Interstate 70 where a rock slide sent boulders as big as vans crashing onto the road.

Road crews, under the glare of portable spotlights, toiled through the night in hopes of reopening one lane of traffic in each direction. But the highway through scenic Glenwood Canyon (search) in western Colorado remained closed Friday morning.

More than three dozen boulders landed on Interstate 70 early Thursday, some embedded 6 feet deep. State officials ended up closing a 24-mile section of the main east-west artery through Colorado. They rerouted Thanksgiving Day traffic that ordinarily flows between Glenwood Springs (search) and Gypsum (search) along an almost 220-mile detour to the north.

Geologists and engineers were working alongside the crews, trying to figure out what caused the slide.

"This is the worst I've seen in my eight years," said Stacey Stegman, spokeswoman for the state transportation department.

No one was injured in the slide, estimated at 100 feet long and 10 feet deep. An overturned truck had forced authorities to temporarily close the interstate earlier Thursday. They were preparing to reopen the road when rocks began rumbling down the canyon walls a mile away.

The slide left holes in the decks of two bridges, damaged guardrails and knocked out two wall panels along westbound lanes of the elevated mountain corridor.

Diann Allen of Redondo Beach, Calif., was just 30 miles from her destination when she learned she wouldn't be traveling any farther on I-70. She'd been headed to Marble to meet her boyfriend's three college-age sons for the first time.

"Everything was going great until I got here," Allen said outside a Gypsum convenience store. "I guess I'll have leftover turkey. It tastes better anyway."

Highway worker David Kuhn had the unenviable job of informing motorists who had not heard about the slide that they were in for a long detour. He also had to accept — and help travelers do the same — the uncertainty of when the road might reopen.

"It could be 10 hours," Kuhn said Thursday. "It could be two days."