Last Updated 10:35 p.m. ET
STEVENS PASS, Wash. - Three skiers were killed Sunday when an avalanche swept them far down an out-of-bounds canyon at a popular resort, but a fourth skier caught up in the slide was saved by a safety device, authorities said.
The four were among three groups of skiers -- about a dozen people in all -- making their way through a foot and a half of fresh snow on the back side of Stevens Pass, in the Cascade Mountains northeast of Seattle, when the avalanche hit.
All were buried to some extent, but the men who died were swept about 1,500 feet down a chute in the Tunnel Creek Canyon area, King County Sheriff's Sgt. Katie Larson said.
Most of the other skiers, all well-equipped, were able to free themselves and rushed to dig out the victims. They performed CPR on the three men to no avail, Larson said.
The fourth skier who was swept far down the mountain, a woman, appeared to avoid a similar fate because of the avalanche safety device she was wearing, Larson said. Larson didn't immediately have other details about the device.
The men who died were believed to be in their 30s and 40s.
"From what I'm told, they were all very knowledgeable, expert skiers," Larson said.
Someone asked Larson if it was okay to be in that area for skiing; she answered, as reported by CBS affiliate KIRO Seattle: "It's an area that is not a groomed area. It is signed 'out of bounds.' And sometimes you ski at your own risk when go into those areas."
The initial reports of the avalanche reached the sheriff's office just after noon, and for some time it wasn't clear whether the other skiers had also been swept up in the slide.
The Northwest Weather and Avalanche Center on Sunday issued a warning for high avalanche danger for areas above 5,000 feet, saying warmer weather could loosen surface snow and trigger a slide on steeper slopes. The elevation of the avalanche wasn't immediately clear.
At mid-afternoon, the temperature at the base of the Stevens Pass ski resort was 24 degrees, with light winds and good visibility. The temperature at the top of the mountain was 22 degrees, according to the resort's website.
John Gifford, the ski area's general manager, said Sunday that the resort had received 19 inches of snow in the past 24 hours. However, it wasn't snowing there Sunday afternoon.
Stevens Pass is one of the most popular outdoor recreation areas in the state, with visitors flocking to the scenic site to go cross-country, back-country and downhill skiing, as well as snowshoeing and backpacking.
It's been a deadly winter in Washington's mountains. Four people disappeared in vicious storms while camping and climbing on Mount Rainier last month. The four remain missing, and authorities have said they're hoping to find their bodies when the snow melts this summer.
Across the West, there had been 13 avalanche deaths this season as of Thursday, according to the Colorado Avalanche Information Center, which tracks avalanche deaths in the U.S.
Experts have said the risk of additional slides could remain high all season. They attribute the dangers in part to a weak base layer of snow caused by a dry winter.
Avalanche deaths are more common in the backcountry than at ski resorts. Out of about 900 avalanche deaths nationwide since the winter of 1950-51, 32 were within terrain that was open for riding at ski resorts, according to the Utah Avalanche Center.
Also Sunday, King County Sheriff's Sgt. Cindi West said a snowboarder was killed in a separate incident at the Alpental ski area east of Seattle. The snowboarder, a man, went over a cliff.