In the struggle to find loved ones, family members and neighbors used chain saws and their bare hands to dig through wreckage that was tangled by the mud into broken piles.

Authorities said they were looking for more than 100 people who had not been heard from since the disaster about 55 miles northeast of Seattle. They predicted that the number of missing would decline as more people are found safe. But the startling initial length of the list added to the anxieties two days after a mile-wide layer of soft earth crashed onto a cluster of homes at the bottom of a river valley.

“The situation is very grim,” Snohomish County Fire District 21 Chief Travis Hots said, stressing that authorities are still in rescue mode and are holding out hope. But he noted: “We have not found anyone alive on this pile since Saturday.”