DAVID GREENE, HOST:
There are now more than 4,500 firefighters battling the blaze in and around Yosemite National Park. The so-called rim fire is now more than 300 square miles in size and it's destroyed more than 100 structures. Thousands more are threatened. But as NPR's Nathan Rott reports, firefighters are making progress doing all they can to protect what's still standing.
NATHAN ROTT, BYLINE: A portable water pump hums away, sucking water from a nearby creek just outside of Yosemite National Park. It's feeding a makeshift sprinkler system, spraying water at two historic ranger cabins. Right now they look like they're made of aluminum foil.
MIKE MARTIN: This is the structure we wanted to protect so we came in and wrapped it, you know, with our fire shelter material.
ROTT: Mike Martin is with the forest service.
MARTIN: And then installed the sprinklers here to put moisture down on the ground and on the structure so it's not receptive to any embers that might land and cause a fire.
ROTT: They're doing everything they can to save these cabins, including a burnout. Just up the hill, firefighters are torching the ground, clearing pine needles and brush with a lit combination of diesel and gas. It should starve the incoming wildfire of fuel.
MARTIN: So I'm walking up a road where a group of firefighters are doing one of those controlled burns that we've been talking about. As we get a little further up, you can hear the trees are really starting to go up.
ROTT: A group of trees torches out, sending flames 50 feet up, but none cross the road. And this is the strategy firefighters are using all over. It's helped contain most of the fire's western flank towards the town of Tuolumne. They're hoping for similar success on the fire's eastern flank in Yosemite. There firefighters will be lighting a massive burnout, more than 20,000 acres in total over the next few days. Nathan Rott, NPR News, Groveland, California. Transcript provided by NPR, Copyright NPR.