A dozen fire victims filed the suit in Kittitas County. They claim Conway Construction and Rainier Steel negligently started the fire that burned 23,000 acres and destroyed dozens of home.
A spokesperson for DNR says the fire's exact cause or origin hasn't been determined.
"A contractor and subcontractor working in conditions such as those has a duty to take reasonable safety precautions to preclude the fire from starting or to suppress it quickly and they clearly failed to do so," said attorney Michael Helgren.
To get all sides, we called Conway Construction and Rainier Steel.
Conway's owner says he hasn't been served any legal papers and stressed the fire was still under investigation.
Helgren expects at least a dozen more victims to join the suit.
Rainier Steel did not return our calls.