Santa Clarita, Calif. ? A wildfire jumped lines dug by firefighters and spread out of control Sunday in northern Los Angeles County, forcing hundreds more families to flee their homes.

Residents of more than 600 homes near Santa Clarita were ordered to evacuate as the fire grew to more than 4,200 acres. An unexpected wind shift had pushed the fire toward houses just hours after officials had lifted an evacuation order affecting only about 80 homes.

By Sunday afternoon, the fire — fanned by winds up to 15 to 20 mph — had moved northeast outside fire lines toward homes in the neighborhood of Fair Oaks, county fire department spokesman Mike Brown said.

No injuries or structural damage was immediately reported from the fire, one of several burning a total of 40,000 acres in the state, from eastern San Diego County to Yosemite National Park.

More than 1,000 firefighters were battling the wildfire, which started Saturday. Its cause is under investigation.

About 90 miles east of downtown Los Angeles in Riverside County, fire officials contained 50 percent of a 3,600-acre fire. Full containment was expected Tuesday morning.

“We’re continuing to improve lines, and we don’t see much more growth in the fire,” said Jim Boano, a spokesman for the California Department of Forestry.

Mandatory evacuation orders were lifted Sunday for about 500 homes, but voluntary evacuations were issued for an additional 200 homes, Boano said. The fire destroyed three single-wide mobile homes, 11 outbuildings and several vehicles.

The fire was started by someone who had been shooting target practice, officials said. The person, whose name was not released, was given a citation and may have to pay a portion of the firefighting costs.

A lightning-sparked wildfire in Yosemite National Park was being allowed to burn because slow-moving flames were cleaning the forest floor of debris that could have fed a more dangerous fire. The blaze has scorched at least 3,000 acres and forced the closure of several popular trails.