Three people were killed on Sunday in an avalanche at a mountain pass in northern area in the U.S. state of Washington, local media reported. Local King TV reported that police confirmed that three were dead and people who were reported missing earlier Sunday have been accounted for. The deaths occurred in an out-of-bounds area near the Stevens Pass ski resort and it is not immediately known what set off the avalanche, said local police. The U.S. Northwest Weather and Avalanche Center on Sunday issued a warning for high avalanche danger for areas above 5,000 feet.