Two avalanches near Washington state ski resorts killed four people on Sunday, but eight others initially said to be missing were found alive, authorities said.

Three skiers died when an avalanche struck near the Stevens Pass ski area in the Cascade Mountains of north-central Washington, King County Sheriff's spokeswoman Sergeant Cindi West said.

She said eight other people listed as missing following the avalanche had been found alive and unharmed.

"There are three confirmed dead," West said. "The other individuals did self-rescue and are fine."

The snow came down at a road about 2 miles (3 km) from Stevens Pass and about 10 miles (16 km) from the town of Skykomish.

In an unrelated incident, West said, a 41-year-old Seattle man was killed in an avalanche at the Alpental ski area while snowboarding out of bounds with friends.

"What the witnesses say is ... he started his own avalanche and the avalanche swept him down the hill and over a cliff, which was about a 500-foot (150-metre) fall," she said.

The Northwest Weather and Avalanche Center warned on Sunday of high avalanche danger above 5,000 feet (1,520 metres)in the Stevens Pass area, with considerable danger at lower altitudes.

The center said heavy snowfall of 30 to 35 inches (76-90 cm) in the area in recent days had triggered avalanches.