Seven people are injured and more than 12 are still unaccounted for after saturated groundwater and heavy rainfall reportedly gave way to the landslide, which affected about one square mile. Search crews are conducting an active rescue as they continue to look for victims in the area.
At least six homes were destroyed and both the road and river continue to be blocked after the incident.
"Total devastation. I mean, it's just unbelievable. It reminds me of what a tornado looks like when it's touched the ground," Sheriff Ty Trenary said.
Authorities are searching both sides of the landslide in their search for survivors, but Snohomish County Fire District 21 Chief Travis Hots said Sunday that the rescue operation should focus on keeping respondents safe as the area continues to be highly unstable.
He went on to compare the mud flow to quicksand noting that the landslide is 15 feet deep in some locations.