Two fire crews from the Valley are part of two separate strike teams sent to the Butts Canyon Fire in Napa and Lake counties.
Glen Ellen sent a Type I engine to the blaze, Kenwood sent a Type III, while Sonoma Fire and Rescue Authority Capt. Sean Lacy is a strike-team leader.
The Glen Ellen crew, consisting of Assistant Chief Matt Atkinson, engineer Marty Amon and firefighters Japen Soto and Will Powers, are on structure protection in the Berryessa Estates subdivision.
Glen Ellen Chief Peter Van Fleet thinks the crew could be released as early as Saturday.
The Kenwood crew, consisting of Assistant Chief Daren Ballach and firefighters Kayla Shubin and AJ Armanini, are part of a Type III strike team.
The blaze, which started Tuesday, has so far burned 4,300 acres in Napa and Lake counties and according to Cal Fire was only 30 percent contained as of noon Thursday.
So far, two homes and seven outbuildings have been destroyed and another 380 structures are threatened.
Cal Fire has almost 1,100 personnel fighting the blaze with 132 engines, 33 fire crews, four air tankers, six helicopters and 18 dozers attached to the fire.
The cause is still under investigation.
According to the Cal Fire web page on the incident, the fire is burning in a mix of grass, brush, oak and pine trees in steep, rugged terrain.