LOS ANGELES (AFP) - Rescuers clawed through piles of mud, rocks and trees early Sunday trying to reach survivors of a giant landslide that killed three people in the northwestern United States.

At least eight people were injured, including a six-month-old infant, when the face of a rain-saturated mountainside slid down on Saturday, destroying six homes in the rural community of Oso, northeast of Seattle, local police and firefighters said.

"We have people who are yelling for help and we are out there," Mr Travis Hots, the district fire chief in Snohomish County, Washington state, told reporters late Saturday.

"This is a massive slide, and we are in a very, very fluid and unstable situation," said Mr Hots. "We are going to take extreme risks to get them out of there."

Search teams used thermal imaging cameras to aid rescue efforts, the Snohomish County sheriff's office said in a statement.

"All of a sudden there was a wall of mud" about 8m high, survivor Robin Youngblood told The Seattle Times newspaper.

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

The landslide destroyed her home.

Eight people have been rescued and are being treated at local hospitals, including a six-month-old baby, Snohomish County spokesman Shari Ireton said on Twitter on Saturday.

"Reverse 911 calls have been going out to residents in the area warning them of the danger of flooding upstream from the slide, as well as the possibility of a downstream flooding should there be a catastrophic breach by the (Stillaguamish) river," Ms Ireton said.

Rain has been especially heavy in the Cascade Mountains region in the past weeks, officials said. The forecast is for a break in the rain Sunday, but more heavy downpours throughout the week.