HOPES are fading for 90 people, including families with children, still missing after a mudslide flattened the outskirts of a rural town in Washington state.

Authorities have warned the death toll from the tragedy in Oso, north-west of Seattle, is expected to rise "substantially". The official number of fatalities stands at 17, based on bodies recovered and identified.

"We always want to hold out hope but I think we have to at some point expect the worst," Snohomish County executive director Gary Haakenson said.

Loading article content