"There is every indication there is not a viable chance of survival," Mount Rainier National Park ranger Fawn Bauer told NBC News. "It's a sad day."
Bauer said crews spotted the climbers' equipment from the air scattered in the snow at the base of a more than 3,000-foot (915-meter) drop leading to a deep chute and steep slope.
The area is prone to rock slides and avalanches, according to the ranger.
The six were last spoken to on Wednesday by satellite phone, the report added. Searchers tried from Friday through Saturday to locate the group, including two guides.
The mountain, an active volcano, is the state's highest.
The searchers could see camping and climbing gear on Carbon Glacier about 9,500 feet up the 14,400-foot mountain, the fifth-tallest mountain in the Lower 48. As they got closer, authorities picked up pings from emergency avalanche beacons apparently buried in the snow. By late afternoon, park officials said that they believed there was no chance of survival because "all indications point toward a fall of 3,300 feet from near the party’s last known location."
Nearly 11,000 people attempted to scale Mt. Rainier in 2013, and in most years about half of those who try reach the top, according to National Park Service statistics. Forty rescue operations were required last year.
Since 1897, at least 89 people have died on Mt. Rainier during summit climbs, according to the park service. In June 1981, 11 climbers were killed after being buried under giant chunks of ice in what's widely regarded as the worst climbing accident in U.S. history. Since then, an average of one death has been recorded each year on Mt. Rainier. Climbers feared dead on Mount Rainier Six climbers haven't been heard from since Wednesday.
"This mountain and Carbon Glacier is very dynamic, with continuous rockfall and ice fall," a park spokeswoman told KOMO-TV. "No one is immune to that, no matter how skilled you are."