If confirmed, the deaths would bring the season's avalanche death toll to the highest recorded in contemporary Utah history.
After a 3 1/2-hour search Friday that yielded no results, crews were scheduled to return to the snow-packed mountainside at 9 a.m. today after a 7 a.m. briefing.
More than 100 rescue workers, dogs and ski patrol members, many of the latter from nearby resorts, scoured the site Friday in what began as a rescue operation but soon became a recovery operation.
The huge slide, triggered about 1:30 p.m., measured 400 to 500 yards across at a depth of 16 to 30 feet Summit County's largest in five years, officials said.
"It sounded like the whole mountain was coming down," said Layton resident C.J. Harris, 18, who was snowboarding with his family.
The avalanche occurred in a backcountry area called Dutch Draw on federal land, just east of The Canyons' highest chairlift, the Ninety Nine 90 Express. A swinging gate marked, "You can die, this is your decision," greets thrill-seekers before they choose to go out of bounds.
Harris said getting to that backcountry area requires a hike to the marked gate that allows access. Since the area is not on resort property, The Canyons does not patrol the area or provide avalanche-control efforts.
"They were somewhere they just shouldn't have been," said Summit County Sheriff Dave Edmunds, whose agency is heading up rescue efforts.
Avalanche danger is extremely high in Summit County right now, he said, and people should stay out of the backcountry because there have been numerous avalanches over the past several days.
The Canyons' trail map warns that the resort doesn't encourage or discourage skiing out of bounds, but if skiers and snowboarders choose, they should carry a beacon, shovel and probe.
Edmunds said searchers could find no beacon signal transmitting from under the many feet of snow Friday.
The hunt was halted about 5 p.m. as night fell. Edmunds said he feared a secondary slide could put searchers in danger. At that point, no bodies or survivors had been found. Today's plan calls for a slow, meticulous search, Edmunds said. Rescuers planned on plotting the mountain into grids and using 30-foot-long poles to probe the snow for possible victims.
The Canyons resort closed three chairlifts after the avalanche so its own ski patrol would be freed to join the search, resort spokeswoman Katie Eldridge said. The resort will be open for normal hours today.
The sheriff's office has had no contact with anyone who was in the avalanche, Edmunds said. Reports came in from about 10 witnesses who were skiing or knew people who were skiing in the area when the avalanche came down.
As patrons left parking lots for the day, resort employees asked each driver if everyone in his party was accounted for.
Just before closing time, Syracuse residents Craig and Cindy Jenkins nervously boarded a gondola to search for their son. They hadn't heard from him in quite some time. Luckily, the pair's story was a happy one, since they were shortly reunited with their son, who hadn't been in any danger.
Those concerned that a family member could be one of those trapped in the avalanche should call the Summit County Sheriff's Office at 1-800-828-8477 or visit www.summitcountysheriff.org.
Roland Kent, 31, was visiting The Canyons from Virginia and said he has skied the avalanche area in the past. The dry, powdery snow in that area is beautiful and deep, he said, but Kent is careful to check avalanche conditions before heading into the backcountry.
Kent was dubious about early rumors that as many as 15 people could have been caught in the avalanche.
"Not a lot go there," the former resident said, adding that most people who ski that area would know the dangers and would know to check beforehand.
Edmunds later confirmed that 15 possible victims was an erroneous report.
A deadly season
In both 2001 and 1997, six people died in Utah avalanches, the highest total in modern history, until now.
So far this season, that number has been matched and possibly surpassed. Since mid-December and prior to Friday's tragedy, six people had been killed in avalanches in Utah this season. The deaths already surpass the total for the entire 2003-04 season, which was four.
The last fatal avalanche near The Canyons resort was nearly five years ago to the day. Greg and Loren Mackay were killed in a massive slide they accidentally triggered in nearly the same area as Friday's slide.
The Mackays used a backcountry access gate near the top of the Ninety Nine 90 chairlift and hiked about a mile behind that peak and across a saddle to Square Top.
The couple was discovered missing after not picking up a 3-year-old son they had dropped off at day-care.
Tom Kimbrough, forecaster with the U.S. Forest Service's Utah Avalanche Center, said the slide that killed the Mackays is north of the Ninety Nine 90 lift. Friday's slide was triggered from about the same distance south of the lift, he said.
Messages recorded Friday morning on the U.S. Forest Service's Utah Avalanche Center's advisory lines cautioned skiers and snowboarders to be extremely careful on steep slopes in the backcountry.
Although the snowpack was becoming more stable, high winds Thursday shifted a lot of snow.
"The avalanche activity is widespread enough to make most avalanche experts nervous," the recorded message said. "It's like playing with an armed nuclear bomb. You can probably keep it from exploding, but do you want to take the chance?"
The danger of another avalanche should continue throughout the weekend, said Bruce Tremper, director of the Utah Avalanche Center.
"Few avalanche professionals can remember weather like this," Tremper said. "Avalanches have been fracturing extremely large, running extremely far and mowing down mature timber. These kinds of conditions occur only once every 10 or 20 years."
The area where Friday's slide occurred was "exactly the sort of slope described in the (recorded) avalanche advisory," Kimbrough said. The area, which is prone to avalanche activity, has the steepness to trigger slides and normally gets loose snow blown onto it from the winds because it's at the top of the ridge.
Kimbrough said he "certainly wouldn't put it out of the question to see more (slides) this weekend" and advised recreationists to be extremely careful.
Copyright 2015, Deseret News Publishing Company