(Updates death toll)
By Jonathan Kaminsky
OLYMPIA, Wash., March 23 (Reuters) - The death toll rose to eight and 18 people were missing on Sunday after a landslide in Washington state that buried homes and cars under mud and debris up to 15 feet (5 m) deep, authorities said.
Eight people were also injured when rain-soaked embankments along State Route 530 near Oso, Washington, about 55 miles (90 km) northeast of Seattle, gave way on Saturday morning and washed out at least six homes.
A spokesman for the Snohomish County Sheriff's Office said a total of eight bodies had been found in the square mile (2.6 square km) of tangled debris, rocks, trees and mud by nightfall.
Snohomish County Fire District 21 Chief Travis Hots told an earlier news conference, "We didn't find anybody alive. There was no sign of life" after a search of much of the area on foot.
The tally of missing was likely to grow, Hots said. The rescue mission was to halt at dusk because of treacherous, quicksand-like conditions, and would resume at dawn on Monday, Hots said.
Some rescue workers had been mired in mud up to their armpits and had to be dragged to safety, authorities said.
Washington Governor Jay Inslee flew over the area on Sunday. He told the news conference, "I have a sense that we're going to have some hard news here."
The slide in the foothills of the Cascade Mountains along the Stillaguamish River piled mud, rock and debris up to 15 feet (5 m) deep in some places.
It blocked the flow of the river, creating floods and a backup of water behind a natural dam of mud and debris, but the threat to people downriver had begun to ease, Inslee said.
The highway was closed in both directions, with no timeline for it to be reopened, he said.
The Snohomish County sheriff's office has asked people affected by the slide to report to the Red Cross so an accurate count can be made of the missing.
Washington state Lieutenant Governor Brad Owen on Saturday evening declared a state of emergency in Snohomish County. (Reporting by Jonathan Kaminsky in Olympia, Washington; Additional reporting and writing by Kevin Murphy in Kansas City, Missouri; Editing by Edith Honan, Cynthia Osterman, Ian Simpson and Eric Walsh)