Update, 8:10 a.m. Thursday: Cal Fire's latest summary of the Grant Fire, the series of blazes that broke out Wednesday afternoon south of Byron and west of Tracy:
The firefighting agency says the fire charred about 500 acres and was 80 percent contained Thursday morning. The fires destroyed one home, three outbuildings, three vehicles, a trailer and a boat.
There's no word yet on the cause of the fires.
Original post: Cal Fire ground crews and helicopters responded Wednesday afternoon to a series of wind-driven fires burning in far eastern Contra Costa and Alameda counties.
Cal Fire reported that it was fighting seven separate fires -- scattered in rolling, grassy terrain over a 10-mile stretch south of Byron and west and south of Tracy -- totaling about 500 acres. The fire agency dispatched both water-dropping helicopters and fixed-wing tankers to stop the blazes.