Just a half hour before an avalanche outside a Utah ski resort trapped as many as five people under 30 feet of snow, skier Jess Fleig sensed that something was amiss.

"I looked at that ride probably 20 or 30 minutes before it went and what immediately came to mind is that's trouble waiting to happen," said Fleig, speaking on a cell phone from a mountaintop.

No bodies or survivors had been found in Friday's avalanche, which was about 500 yards wide and happened outside the boundary of The Canyons resort on federal land in the Wasatch-Cache National Forest (search).

Before stopping the search for the day, authorities changed the focus of the operation from rescue to recovery.

"I think it's safe to say the odds of surviving are very, very low," Summit County Sheriff Dave Edmunds said.

The area where the avalanche occurred was marked with a skull and crossbones to discourage thrill-seekers. Fleig, a 35-year-old disc jockey, said he frequents the backcountry but stayed away from that area Friday.

Based on eyewitness accounts of the slide, Summit County Sheriff Dave Edmunds estimated that between two and five people were trapped.

About 100 search and rescue workers, rescue dog crews and members of ski patrols from Summit County resorts searched the area for victims, Edmunds said. The enormity of the slide was underscored when rescuers, working on 30-degree slopes, found that their 20-foot probes weren't going deep enough into the snow.

The rescue effort was halted before sunset because of concerns over secondary slides, Edmunds said. The "slow and meticulous" search was to resume Saturday morning, he said.

Even before Friday, this had already been one of the deadliest winters for avalanches in Utah since records were first kept in 1951. Before Friday six people had died in slides; no previous winter had seen more than six deaths.

Bruce Tremper, director of the Utah Avalanche Center (search), said the area where the slide happened was out-of-bounds, but the resort "can't close it off. It would be like trying to close a city park," Tremper said.

The Utah Avalanche Center warned of considerable avalanche danger Friday, which means human triggered avalanches were probable.

A series of storms lasting over two weeks dropped 6-8 feet of wet, heavy snow on the Wasatch mountains, setting up prime avalanche conditions.