Crews made more progress early Thursday fighting the McCain fire in East County near Boulevard and had it 70 percent contained by 7 a.m., Cal Fire San Diego said. The blaze was the latest warning for San Diego County in what is already shaping up to be a fierce fire season statewide. A historic heat wave across California has heightened concerns this week, particularly with the risk posed by Fourth of July fireworks. The McCain fire began Monday after a car crash on Interstate 8 caught nearby brush on fire near McCain Valley Road. Firefighters on Thursday were continuing to work on cutting a containment line around the fire. “It’s a huge amount that we still got to cut out to make sure that it doesn’t spread,” said Capt. Thomas Shoots. “We’re hoping to start winding down over the next couple days, really hit it hard today and tomorrow.” The fire has now burned about 1,600 acres. The hope is to have it fully contained this weekend, Shoots said. Cal Fire has so far deployed more than 220 personnel, seven crews, 14 engines, four helicopters, two dozers and two water tankers to the McCain fire. The blaze forced an evacuation of De Anza Springs Resort, a motel and recreational vehicle site earlier this week; that evacuation order has since been lifted. Besides the moderate injuries sustained by the driver whose car crashed on Monday, there have been no injuries or structures damaged in the McCain fire, Shoots said.