Before crews could get onto the debris field late Sunday morning, they looked for people by helicopter. They had late Saturday heard people yelling for help, but they were unable to reach anyone. The soupy mud was so thick and deep that searchers had to turn back.
"We have this huge square-mile mudflow that's basically like quicksand," Hots said Sunday.
The slide wiped through what neighbors described as a former fishing village of small homes — some nearly 100 years old.
As the search for the missing continued, authorities said some may have been able to get out on their own. The number unaccounted for could change because some people may have been in cars and on roads when the slide hit just before 11 a.m. Saturday.
Officials described the mudslide as "a big wall of mud and debris." It blocked about a mile of State Route 530 near the town of Oso, about 55 miles north of Seattle.
Authorities believe the slide was caused by ground made unstable by recent heavy rainfall.
Washington Gov. Jay Inslee described the scene as "a square mile of total devastation" after flying over the disaster area midday Sunday. He assured families that everything was being done to find their missing loved ones.
The slide blocked the North Fork of the Stillaguamish River. With the water pooling behind the debris, authorities worried about downstream flooding and issued an evacuation notice Saturday. The water had begun to seep through the blockage Sunday afternoon, alleviating some concerns.
Snohomish County officials said Sunday that residents could return home during daylight hours. Even though the evacuation had been lifted, Inslee urged residents to remain alert.
The National Weather Service issued a flash flood watch for Snohomish County through Monday afternoon.
Shari Ireton, a spokeswoman for the Snohomish County sheriff's office, said Sunday that a total of eight people were injured in the slide.