At least three people have been killed and 18 are missing in a huge landslide in the north-western US state of Washington, officials say.

A large rescue operation began soon after the landslide struck on Saturday.

The landslide injured seven people, destroyed 30 houses and covered a road near the town of Oso, about 90km (55 miles) north of Seattle.

It was at least 41m (135ft) wide and 54m deep, local authorities said.

They say that two people were killed at the scene and one died in hospital. The injured included a six-month-old boy.

'Wall of mud'

An eyewitness told the Daily Herald that he was driving on the road 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 thee 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."

Residents reported hearing cries from those trapped, but local fire chief Travis Hots said the dangerous conditions were hampering the rescue effort.

The landslide cut off the city of Darrington and clogged the North Fork of the Stillaguamish River, prompting fears of severe flooding downstream if the build-up of water behind the debris breaks through suddenly.

The authorities say the landslide was caused by recent heavy rain.

More rain is expected in parts of Washington on Sunday, and some people have been advised to move to higher ground.

The area has had problems in the past with unstable land.

Source: BBC