A weekend landslide in the foothills of the Cascade Mountains in Washington state has killed at least eight people and left another 18 unaccounted for, as hopes of finding survivors in the massive field of debris begins to fade.

Saturday morning a rain-soaked embankment gave way, triggering a one-square-mile landslide that reportedly destroyed 30 homes along State Route 530 near Oso, about 55 miles northeast of Seattle.

The landslide left a soupy, tree- and debris-littered aftermath that was as many as 15 feet deep in some places, creating difficult and dangerous conditions for a search and rescue operation. Some rescue workers had to be rescued themselves after becoming stuck in shoulder-deep mud, according to Reuters.

The search for survivors and victims is scheduled to continue Monday after the perilous conditions forced the rescue operation to be suspended at dusk Sunday.

Five bodies were found in the wreckage Sunday afternoon, bringing the confirmed death toll to eight, according to the The Daily Herald of Everett, Wash.

The number of people still missing is unclear, as people driving along State Route 530 at the time of the incident - about 10:30 a.m. - could have been buried along with people who were on their property at the time of the landslide. At least 18 people are missing, but it could turn out to be more, officials said.

Saturday evening rescue workers heard voices of people calling from the debris, but dark and dangerous conditions forced crews to suspend their operation until daybreak. By Sunday morning there were no signs of life.

"We didn't see or hear any signs of life out there today," Snohomish County Fire District 21 Chief Travis Hots said, according to The Associated Press. "It's very disappointing to all emergency responders on scene."

Landslides are not unknown in the area. In 2006, part of the same hillside broke away and dammed a river just south of the neighborhood where Saturday's disaster occurred, The Daily Herald reported, adding that no one was hurt in that incident.

Nearly one year ago, a huge landslide on Whidbey Island in western Washington knocked one home off its foundation and caused the evacuation of more than 30 others after a stretch of land the length of five football fields fell from the island ridge.