A fast-moving brush fire south of Gilroy quickly spread to 150 acres Sunday afternoon before fire crews stopped its forward progress about five hours later, according to Cal Fire.
The blaze was burning off Castro Valley Road, west of Highway 101 in south Santa Clara County, near Gavilan College, and air support and other resources were helping with the firefight, fire officials said.
The fire, dubbed the Castro Fire, started about 4 p.m. and spread to 50 acres within an hour, with no containment. Later Sunday, before the the blaze was three hours old, it had spread to 150 acres and was 20 percent contained, fire officials said.
By late Sunday night, Cal Fire said the fire's forward progress had been stopped, and it was 50 percent contained.
No structures were threatened and no evacuations were issued as of Sunday night, Cal Fire said.
Fire crews were expected to remain at the scene overnight, officials said.