Four people were killed in two avalanches that swept through an area near a ski resort in the northwestern US state of Washington, authorities said.

US media initially reported that at least eight others were missing in the incidents, which took place Sunday near Stevens Pass in the Cascade Mountains northeast of Seattle.

But King County Sheriff's Office spokeswoman Kathleen Larson said the eight had "managed to to dig themselves out of the snow."

However, three skiers who were part of that group did not make it out alive, and efforts to revive them through CPR procedures had been unsuccessful.

Officials said the group was skiing in a restricted, avalanche-prone area that was marked by clear signs warning people of the danger.

Meanwhile, a second avalanche, near the ski resort of Alpental, buried a snowboarder, officials said. The man was found a half-hour later but efforts to revive him were also unsuccessful.

The Northwest Weather and Avalanche Center on Sunday had issued a warning about "high avalanche danger" above 5,000 feet (1,500 meters), and a "considerable" danger below that elevation.

It was not immediately clear the elevation at which the avalanches occurred.