Washington authorities have found six more bodies after Saturday’s huge landslide, bringing the number known to have been killed to 14, say police.
Officials now say as many as 176 people may remain unaccounted for after the 177ft wall of mud hit near the town of Oso, north of Seattle.
Search crews have worked day and night, using helicopters and laser imaging.
Officials admit they have little hope of finding survivors.
President Barack Obama has declared an emergency in Washington State and ordered federal authorities to co-ordinate the disaster relief effort.
Speaking earlier after surveying the area from the air, Washington Governor Jay Inslee said it was “devastation beyond imagination”.
Jay Inslee said the slide “basically cut a mountain in two” and deposited it on the town below. Nothing in the path of the slide was still standing.
“It’s that absolute devastation that causes us all real pain,” he said.
Family members and volunteers were using chainsaws and their bare hands to shift the wreckage and try to find those missing.
At a news conference on Monday evening, Snohomish County emergency management director John Pennington said the official list of the missing stood at 176.
But he said he did not think the final death toll would be so high, because some of those listed as unaccounted for would be found to be alive, and other names would prove to be duplicates.
But he said authorities no longer expected to find survivors in the debris.
“We as a community, we as a county, are beginning to realize that we are moving toward a recovery operation,” John Pennington said.
“There is an awful lot of grieving.”
The landslide left behind a cliff known as a head scarp 600ft high, Washington state geologist Dave Norman told reporters on Monday afternoon.
Authorities have continued their search-and-rescue operations amid a tangled, water-logged field of mud and debris, using rescue dogs, aerial photography and laser imaging to help the search.
Officials said the conditions were treacherous, and the threat of further landslides on Monday forced the authorities to pull rescue workers back from the scene briefly until scientists determined there was no further risk.
More than 30 homes were destroyed and more than half the town of Oso is missing – a recent census put its population at 180.
The landslide cut off the city of Darrington and clogged the north fork of the Stillaguamish River.
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