SEATTLE (AP) - Three people are dead and as many as eight are missing after an avalanche Sunday near a popular ski resort in Washington state that received heavy snowfall overnight, authorities said. The King County Sheriff's Office began receiving word about the slide near the Stevens Pass ski area just after noon, Sgt. Cindi West said. Stevens Pass is in the Cascade Mountains, about 80 miles northeast of Seattle. The avalanche happened in an out-of-bounds area on the back side of the resort. Search and rescue crews and other emergency responders were at the scene. 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. At mid-afternoon, the temperate at the base of the 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 the resort has received 19 inches of snow in the past 24 hours. However, he said it wasn't snowing there Sunday afternoon, and he had no details about the slide. Stevens Pass is one of the most popular outdoor recreation areas in the state, with visitors flocking there 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 Feb. 16, 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, West said a snowboarder was killed in a separate incident at the Alpental ski area east of Seattle. The snowboarder went over a cliff. No other details were available.