Officials said Saturday that the six climbers were likely to have fallen 3,300 feet (1,000 meters) to their deaths from the north face of the mountain in what would be the worst accident on Mount Rainier in three decades.
Helicopter crews found climbing and camping gear in snow more than 3,000 feet (900 meters) below the climbers' last known position and also picked up distress signals from the group's avalanche beacons.
A park spokeswoman said the climbers appeared to have fallen or been caught in an avalanche of snow, rock and other debris.
The climbing party, including two guides from Seattle's Alpine Ascents International, had set off on Monday for a five-day trek intended to take them up one of the toughest ascents of the ice-covered 14,100 foot (4,298 meter) massif.
They were last heard from via satellite phone on Wednesday evening, when they had reached a height of 12,800 feet (3,900 meters).
The climbers indicated they were fine and planned to reach the summit on Thursday, but noted that bad weather seemed to be moving in. Bauer said a rain and hail storm that swept through the area Wednesday had produced snow at higher elevations.
Alpine Ascents' website describes the Liberty Ridge hike as "one of the most technical and physically demanding climbs we do in the lower 48 states".
"The larger Alpine Ascents community and families are stunned and grief stricken," a statement from the group said.
The identities of the climbers were not released.
The accident was the worst at Rainier since 1981, when an ice fall killed 11 hikers.
Mount Rainier, an active volcano, is part of the Cascade Range, and dominates the Seattle skyline.