The fire was first reported at 6:30 p.m. and by 10 p.m. had grown to 30 to 40 acres, according to Kent Sisson with the Chelan County sheriff's office.
Sisson said deputies and firefighters issued a level three evacuation notice to roughly 40 homes. Level three evacuations, which are the most serious, mean residents must leave immediately, Sisson said.
Most of the evacuees were moved to a nearbyYMCA or the local fire station.
As of 10 p.m., four structures, all of which were unoccupied, were burned. Sisson said the fire is threatening several other homes and cabins along the lake.
Local and U.S. Forest Service fire crews are battling the fire, and Sisson said dying winds are helping them get a handle on it.
There's no word yet on what sparked the fire.