Firefighters battled two fires in East Contra Costa County late Sunday, both of which threatened structures, fire officials said.
The first fire started a little after 7 p.m. at the Highway 4-Highway 160 interchange in Antioch after a disabled vehicle pulled over and sparked nearby brush, officials said.
The blaze quickly spread to 20 acres and three alarms as it burned up the side of the freeway, threatening about 100 homes and other structures, fire officials said.
Bull dozers were dispatched to the scene to keep the fire from reaching those structures, officials said.
As crews were mopping up the Antioch fire about 8 p.m., they could see a fire in nearby Brentwood. Crews cut loose from the Antioch fire rushed over to Brentwood to help battle that blaze, which reportedly was threatening at least 10 homes and a shopping center.
"We have a new neighborhood going in there, and some of the houses there are in the framing phase," East Contra Costa Fire District Battalion Chief Ross Macumber said. "So we took that very seriously and sent one of our units there first to go protect those structures and make sure we didn't burn those new houses down."
The cause of the Brentwood fire was unknown and being investigated.