Media playback is unsupported on your device Media caption Authorities confirm that 108 people have been reported missing

Authorities say they have 108 reports of people missing or unaccounted for after Saturday's huge landslide in the north-western US state of Washington.

Eight bodies have been recovered so far after the 177ft (54m) wall of mud swept near the town of Oso, about 55 miles (90km) north of Seattle.

Search crews have worked day and night, using helicopters in the dangerous conditions that destroyed 30 homes.

Several people, including an infant, were critically injured.

"This is devastation beyond imagination," Washington Governor Jay Inslee said after surveying the area from the air.

He 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, he said. "It's that absolute devastation that causes us all real pain."

'Situation very grim'

Snohomish County emergency management director John Pennington said the figure of 108 missing did not necessarily represent the total number of injuries or fatalities.

Image copyright AP Image caption The wreckage of a home after the mudslide

Image copyright Reuters Image caption The landslide is said to have destroyed 30 homes in the area

Image copyright Reuters Image caption The authorities say the landslide was caused by recent heavy rain

He said the list had been consolidated from a number of sources.

"It's a soft 108," Mr Pennington told a news conference, reports the Associated Press news agency.

The number is expected to fall as it is suspected that some of the missing-person reports have overlapped.

Mr Pennington added: "We have not found anyone alive on this pile since Saturday."

Snohomish County fire chief Travis Hots told reporters: "The situation is very grim."

More than half of Oso is missing - a recent census put its population at 180.

'Gone in three seconds'

Image copyright AP Image caption Oso Community Church displays a sign reading "pray with us for our community"

Image copyright AP Image caption A man walks across the rubble on the east side of the mudslide

Image copyright Reuters Image caption The thick mud covered a square mile and was up to 40ft deep in places

The landslide left behind a cliff known as a head scarp 600ft high, Washington state geologist Dave Norman told reporters on Monday afternoon.

"This is one of the biggest landslides I've seen," Mr Norman said.

Authorities have continued their search-and-rescue operations amid a tangled, water-logged field of muck and debris.

They say the conditions are treacherous, and the threat of further landslides had forced some search-and-rescue workers to withdraw on Monday.

"There is still some movement on the landslide, and so that is something that we're trying to get a better handle on," Mr Norman said.

He said scientists were surveying the site using lasers and aerial photography.

An 81-year-old man and a six-month-old boy were said to be in critical condition at a Seattle hospital on Sunday.

An eyewitness told the Daily Herald that he was driving on the road near Oso and had to quickly brake to avoid the mudslide.

"I just saw the darkness coming across the road. Everything was gone in three seconds," Paulo Falcao told the newspaper.

Robin Youngblood, another witness, told the Seattle Times: "All of a sudden there was a wall of mud. Then it hit and we were rolling.

"The house was in sticks. We were buried under things, and we dug ourselves out."

The landslide cut off the city of Darrington and clogged the north fork of the Stillaguamish River.

Mr Norman said the river had begun to flow over the debris, relieving the water pressure in the part of the river blocked behind the landslide and lessening the chances of a catastrophic flood if the water should break through all at once.

The authorities say the landslide was caused by recent heavy rain, although Mr Norman said the area's terrain was made up of unstable glacial sediment and had been subject to landslides since the last ice age.

He said landslides occurred in the area in 2006 and 1969.