Firefighters were working to contain a brushfire that consumed 150 acres south of Gilroy on Sunday afternoon, the California Department of Forestry and Fire Protection said. The fire, which firefighters said was 50 percent contained by midevening, was burning in a hilly expanse west of Highway 101 near Castro Valley Road, and flames and smoke were visible in nearby areas. No structures were threatened, fire officials said. Steve Rubenstein is a San Francisco Chronicle staff writer.