Avalanches claim 13 lives across USA's West this season

Three people were killed Sunday in an avalanche near a ski resort in Washington state, officials with the King County Sheriff's Office said. Spokeswoman Katie Larson said several groups of skiers were caught in the deadly rush.

"Almost all of them -- probably up to 12 at some point -- are buried in the snow. They manage to dig themselves out ... At that point then, they look and they find that three of these skiers are suffering from medical issues. They begin CPR and, unfortunately, they were not able to resuscitate the victims," she said, adding that everyone was accounted for, according to CNN International.

Larson said the men were among three groups of people skiing out-of-bounds at the Stevens Pass ski area. The fourth person who was swept down the mountain, a woman, wasn't seriously injured.

Also Sunday, the Sheriff's Office said, a snowboarder was killed in a separate incident at the Alpental ski area east of Seattle. The snowboarder went over a cliff, says Detroit Free Press.

The men skied past a sign warning them that the area was out-of-bounds and that skiing was at their own risk, Larson said. Earlier Sunday, the Sheriff's Office said as many as eight others were missing in the Stevens Pass avalanche, but authorities later said they were accounted for.

The snowboarder's friends safely returned to the mountain's base and called for help, but rescue workers were unable to find him until an hour and a half later. By the time they reached him, the snowboarder could not be revived, informs San Francisco Chronicle.

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 in the region 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, reports ABC News.