The fire started just after 2 p.m. Thursday near East Mason Lake and East MacEwan Prairie roads by Rainbow Lake. It was 40 percent contained as of Friday evening.
The residents of 12 homes near Rainbow Lake and 12 homes on Johns Prairie Road evacuated Thursday night, but residents since have been allowed to return, said DNR information officer Sarah Foster.
Foster was unaware of any additional evacuations Friday.
Fire crews from all over Western Washington were heading to Shelton on Friday to relieve firefighters from Mason, Thurston and Grays Harbor counties who have been fighting the blaze since it began.
A Type II Incident Command team took control of the fire Thursday night. About 200 firefighters and two DNR helicopters are assisting.
The cause of the blaze is under investigation.
“We know there wasn’t any lightning in the area when the fire started, so it’s definitely something that was human-caused,” Foster said. “But it could have been anything. … As dry as it is, any spark can cause a fire like this.”
The fire seemed to be calming Friday morning, but as winds picked up in the afternoon, smoke began to billow.
“It’s an active fire again,” Foster said. “It’s bigger than the fires we are used to in Western Washington, and it’s unheard of for October.”
The fire is continuing to burn along power lines in scotch broom, grass and timber, putting up large amounts of smoke, Foster said.