A fire spokeswoman says a new Western Washington wildfire burning northeast of Shelton is threatening 100 structures - including at least a dozen homes - and has grown to 150 acres.

More than 100 firefighters from three counties planned to work through the night protecting homes and battling the flames. Spokeswoman Sarah Foster says winds have calmed and the temperature is dropping - both good signs. Foster says additional fire crews from across the state can be tapped Friday.

Foster says the 100 structures include all the buildings in the "big box of where the fire is." She wasn't sure late Thursday night how many homes were included in that number. Residents of about a dozen homes have been told to evacuate.

Flames have been burning under Bonneville Power Administration power lines. Foster says a large Mason County Public Utility District building is close to the fire.

The fire that started Thursday afternoon is 10 percent contained.

No injuries have been reported.

The area is about 45 miles southwest of Seattle.