Fire crews contained an 840-acre blaze that started Tuesday afternoon near Don Pedro Reservoir.
Cal Fire announced Wednesday morning that crews had stopped the forward spread of the fire located off Paseo Seven Legends Road east of La Grange Road.
The fire burned mainly grass and oak woodland, but an outbuilding of a nearby ranch was also destroyed, said Cal Fire spokeswoman Lisa Williams.
No one was injured during the firefight, she said.
At one point, there were more than 100 firefighters battling the blaze, including 12 engines, three hand crews, three water tenders, two air tankers, one dozer and a helicopter, according to Williams.
There was also a wildfire near La Grange that started about 1 p.m. on Tuesday, but crews were able to contain it in under six hours.
That fire burned about 100 acres on the 4000 block of La Grange Road. There were no injuries reported and no structures were damaged.
Eight additional wildfires were raging simultaneously Tuesday night across California in Colusa County, Monterey, and the San Bernardino and Mendoncino national forests, charring a combined total of more than 20,000 acres of land.