Officials in California ordered some residents east of the city of Fresno to evacuate their homes as wildfires ignited by lightning this week spread to more than 10,000 acres on Thursday, threatening over 700 homes and disrupting power and communication lines.

The fires formed from the more than 1,000 lightning strikes that struck eastern Fresno County in the span of three hours on Monday, said California’s firefighting agency, Cal Fire. By Thursday, a crew of more than 1,500 firefighters battled three large fires and several smaller ones, which fire officials called the Fresno June Lightning complex.

The blazes were some of the largest wildfires that have burned in California during what has already been an unusually active year. Wildfires have burned more than 112,000 acres in the state this year, far outpacing the five-year average of 20,500 acres, Cal Fire said.

While the size of the fires near Fresno has swelled over the past few days, the containment has strengthened, too, as firefighters worked to merge some of the fires, a tactic to stop them from spreading by encircling them, according to Sergio Arellano, a spokesman for Cal Fire.

Around 6:40 p.m. on Thursday, Cal Fire said the fires were 34 percent contained. Firefighters were likely to cover more ground overnight as lower temperatures raised the relative humidity of the air, Mr. Arellano said.

“The containment lines are holding well,” he said, adding that he expected the evacuation orders and warnings to be lifted in the next day or two.

The National Weather Service warned on Thursday that dry and gusty conditions were expected over the weekend, bringing a heightened risk of grass fires across the region.