Media playback is unsupported on your device Media caption Aerial footage shows the damage caused by the Oso landslide, as David Willis reports

President Barack Obama has called on Americans to pray for the victims of a mudslide in the US state of Washington which has claimed at least 14 lives.

Officials say as many as 176 people remain unaccounted for after the 177ft (54m) wall of mud hit near the town of Oso, north of Seattle, on Saturday.

Emergency officials said they expected the death toll to rise throughout Tuesday as they comb the debris field.

Search crews have worked day and night, using helicopters and laser imaging.

"The total fatality rate remains at 14 and we're expecting that number to go up throughout the day," local fire chief Travis Hots told reporters on Tuesday.

'Devastation beyond imagination'

At a news conference in the Netherlands earlier, President Obama asked all Americans to send their thoughts and prayers to the victims.

"We know that part of this tightly knit community has been lost," he said.

"We hope for the best, but recognise this is a tough situation."

At the scene The rescuers' faces tell their own sad story. Many have returned looking tired and drawn, their search for friends and loved ones amid the massive mound of mud thwarted by the sheer complexity of the task. The mud is 20ft deep in places. It can take more than 15 minutes to walk a couple of feet. A few hours after the mud came barrelling down the mountainside, flattening everything in its path, cries for help could be heard coming from the wreckage. Now the site is silent, and officials admit there is little chance of finding anyone else alive. As if to prove the point, one of the rescuers discovered his front door amidst the wreckage. But the rest of his house is still missing - along with his wife and child.

He has declared an emergency in Washington state and ordered federal authorities to co-ordinate the disaster relief effort.

Washington Governor Jay Inslee - after surveying the area from the air - said it was "devastation beyond imagination".

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.

Family members and volunteers were using chainsaws and their bare hands to shift the wreckage and try to find those missing.

Cory Kuntz, helped by others, cut through the roof of his uncle's house, which was swept about 450ft from its original site.

He said his aunt, Linda McPherson, had been killed. He and the others pulled files and personal effects from the house.

"When you look at it, you just kind of go in shock," he said.

'Awful lot of grieving'

Worst landslides in recent years China, 2010: Landslide hits several villages in north-west of country, killing at least 1,200 people. Philippines, 2006: Mudslides caused by Typhoon Durian kill at least 1,000 in Southern Leyte. Venezuela, 1999: 10,000 - 30,000 die as landslide hits a coastal town, washing many into the sea. Honduras, 1998: Landslide triggered by Hurricane Mitch kills 6,000 and leaves a million homeless.

Gail Moffett, a retired firefighter, said she knew about 25 people who were missing, including entire families with young children.

Snohomish County emergency management director John Pennington has said the official list of the missing stood at 176.

But he added 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.

About 30 homes were destroyed and more than half the town of Oso is missing - a recent census put its population at 180.

Image copyright AP Image caption A dog aided authorities in search efforts on Tuesday

Image copyright AP Image caption More than two dozen homes were destroyed in the deadly mudslide

Image copyright AP Image caption The size of the landslide became evident from aerial photographs

Image copyright Reuters Image caption Rescue workers, shown here with a dog, have had their efforts hindered by the unstable, water-logged mud and debris that buried the town