CONCORD (CBS SF) — A fast-moving grass fire threatened homes and forced evacuations in Concord Friday afternoon before firefighters gained the upper hand.

Fire officials say sparks from a pickup truck may have ignited dried roadside grasses near Ygnacio Valley Road and which, by 10 p.m., was 85 percent contained after burning 268 acres on and around Lime Ridge Open Space, a Contra Costa County Fire Protection District official said.

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Residents of between 200 and 300 homes in the Crystyl Ranch and Montecito subdivisions, on the outermost southwestern reaches of Concord, were allowed to return home by about 10:15 p.m. following mandatory evacuations earlier in the day, said county Fire Marshal Robert Marshall.

No houses or other structures were damaged but two firefighters sustained minor burns from which they should recover fully, Marshall said.

Lime Ridge Brush Fire

Fire crews battled a 4-alarm brush fire in the hills above Concord on Friday afternoon. (CBS)

CCCFPD firefighters got help from most Contra Costa-based fire departments, Cal Fire and strike teams from Solano and Alameda counties, Marshall said. Retardant-dropping planes from Cal Fire, and helicopters from the East Bay Regional Park District and the Contra Costa County Sheriff’s Department, also were used in fighting the fire.

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Ygnacio Valley Road, a key commute route between central and east Contra Costa County, was closed between Oak Grove Road in Walnut Creek and Cowell Road in Concord for about four hours Friday, reopening about 8:30 p.m.

Fire threatening housing development near Ygnacio Valley Road. (CBS)

That closure had ripple effects throughout the area and helped snarl traffic on other commute routes including Highway 242, Highway 4, Willow Pass Road and even Bailey Road.

Fire crews were expected to be on the fire scene throughout the night, Marshall said.

Fire officials said that a diesel pickup truck spotted with sparks coming from its exhaust pipe may have spawned the fire.

The Bay Area was bracing for another hot weekend with inland temperatures set to approach the 100-degree mark and red-flag fire warnings likely for parts of the East Bay.

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