UPDATE: Mudflow is "too dangerous" for ground search Sunday morning. Map and more updates here: http://cbc.ca/1.2583372 


Rescue crews searched into the night for survivors from a massive mudslide in Washington state that killed at least three people, after hearing voices from the debris field pleading for help.

The slide of mud, trees and rocks happened about 11 a.m. Saturday morning. At least eight people - including a 6-month old boy - were critically injured and at least six houses were destroyed.

Snohomish County Fire District 21 Chief Travis Hots said at a news briefing late Saturday that searchers weren't giving up on finding more people.

"We have people who are yelling for our help, and we are going to take extreme risks," Hots said.

It wasn't clear how many people might still be alive, he said.

"This is still a rescue mission until we determine otherwise," Hots said.

The sheriff said the identities of two victims found among the debris would be confirmed by a medical examiner. The third was rescued alive but died in hospital Saturday afternoon.

The mudslide was first reported at around 10:45 a.m. PT, in the 29400 block of Route 530 towards Arlington, officials say.

Snohomish mudslide - 2

This is the first Tweeted photo of the slide, taken by Traci Reuwsaat at 11:05 a.m. She is asking people who want to help to make donations through Darrington REF or the Red Cross. (@traciroo54/Twitter/)

The Washington Department of Transportation says mud, trees and building materials swept across State Route 530 near the town of Oso, about 20 kilometres east of Arlington.

Washington State Patrol said earlier that the house that was carried across the road had people inside it at the time.

Trooper Mark Francis said the mudslide, which is blocking both directions of the rural road,  is estimated to be 1.6 kilometres long.

Search and rescue operations are underway by Snohomish County crews and the Washington State Patrol.

Spokesman Bart Treece of the Washington State Department of Transportation says he doesn't know how long the two-lane rural road will be closed.

'Stay away from the river'

The slide has cut off the city of Darrington, to the east, and is blocking the North Fork of the Stillaguamish River at Whitman Rd.

As of 4 p.m. PT, Snohomish County officials began warning the public to stay away from the exposed Stillaguamish riverbed, and from all trestles and bridges across the river.

Officials with the County say there is a "very high potential for quick and catastrophic flooding both upstream and downstream of the block."

The National Weather Service in Seattle reports that the river gauge downstream reported a drop of 26 inches.

"It is extremely dangerous to be in or near the Stillaguamish River downstream of the landslide," the Sheriff's Office said, as relayed through the county's Facebook page. "Water behind the landslide could break through at any moment. Please advise the public immediately to stay away from the river downstream of the slide." 

As of 5 p.m. PT, county officials had not issued an evacuation notice, but were trying to reach out to area residents to ask them to be ready to leave at a moment's notice.

"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 river," the County said in a public Facebook update.

Get 'to high ground before nightfall'

By 5:30 p.m. PT, county officials said the status of the landslide had changed.

"There's a very significant risk that if the landslide dam breaks, a large wall of water may flow downstream along the N. Fork of the Stillaguamish through Arlington and Stanwood," the Snohomish County Facebook page said.

Snohomish mudslide - 7

Snohomish County crews and the Washington State Patrol launched a search and rescue effort after a mudslide swept a house with people inside across a rural road. At least five other homes are believed to have been destroyed in the slide. (@wspd7pio/Twitter/Washington State Patrol)

"Anyone who lives in the flood plain of the Stillaguamish River between Oso and Stanwood is strongly encouraged to evacuate to high ground before nightfall. Please be prepared to stay until daylight tomorrow," it said.

"This is official. This is not a drill. Please prepare now to evacuate if you live in the Stillaguamish flood plain between Oso and Stanwood," officials said.

Snohomish County and disaster response officials are expected to re-assess the situation during daylight hours Sunday.

State geology experts were already brought in Saturday to begin assessment of the scene and further hazards, and to determine the cause of the slide.

The Sherriff's Office said that heavy rains are likely to have played a factor.

"The cause of the slide is believed to be ground water saturation from heavy rainfall in the area previously this month," the office said.

Map: area of slide (29400 block Route 530)

With files from The Associated Press