(Recasts with latest acreage figures, evacuation status, quotes; adds byline)
By Victoria Cavaliere
SEATTLE, July 19 (Reuters) - A wildfire raging unchecked for a sixth day east of Washington state's Cascade Mountains has destroyed about 100 homes, displaced hundreds of residents and left thousands without electricity, emergency officials said on Saturday.
A cluster of lightning-sparked blazes that merged days ago into a conflagration dubbed the Carlton Complex has scorched at least 336 square miles (870 sq km) of dry timber and grasslands in north-central Washington since Monday, officials said.
No serious injuries have been reported, said Mike Worden, manager of the emergency dispatch and communications center for the Okanogan County Sheriff's Office.
But authorities were seeking the whereabouts of a "handful" of people - fewer than 10 - who have not been heard from by family or friends in the hardest-hit area of the fire zone, the small Columbia River town of Pateros, Worden told Reuters.
He said authorities had yet to thoroughly canvass neighborhoods left in ruins by the blaze, about 120 miles (195 km) northeast of Seattle, but hoped those unaccounted for would turn up safe.
"They could be just out of touch," he said, noting that cell phone communication in and around the community was spotty and that electricity had been knocked out across the picturesque Methow Valley, home to roughly 10,000 people.
He said fire had damaged transmission lines in the area.
An estimated 100 homes in Pateros were destroyed by the fire, most of them on Thursday, as flames roared into the town of 650 residents, prompting evacuation of the entire community.
Although the immediate threat subsided on Friday as the flames changed course, residents of Pateros were advised to keep their distance for the time being, officials said.
The nearby village of Malott remained under evacuation for a second day, Worden said, and residents near the adjacent community of Alta Lake were told to leave on Friday. Those two areas are home to about 400 people combined.
Emergency officials said they hoped a slight cooling trend and rising humidity levels would help fire crews begin to gain some ground against the wind-whipped blaze by Sunday.
The Carlton Complex was one of about 18 major wildfires burning on Friday across the Pacific Northwest. The governors of Oregon and Washington each declared fire emergencies earlier in the week.
The region's biggest fire, the lightning-sparked Buzzard Complex, has burned about 575 square miles of rangeland in eastern Oregon and was about one-fifth contained, said Rita Dyer, a fire spokeswoman. (Additional reporting and writing by Steve Gorman from Los Angeles; Editing by Paul Tait)