Firefighters in ((the western U.S. state of)) California say inaccessible, steep terrain and extreme fire behavior are hampering efforts to contain a massive wildfire that is threatening a famous national park.
Nearly 5,000 firefighters are battling the Rim Fire but have had to rely heavily on aircraft to slow the spread of the fire.
The U.S. Forest Service said Friday the massive blaze has swelled to more that 800 square kilometers and consumed about 82,000 hectares of land, including some of Yosemite National Park.
The fire is about one-third contained. Authorities are using an unmanned military Predator drone, similar to those used in Afghanistan, to provide information on new fires they would otherwise not be able to see.
The U.S. Forest Service says firefighters expect to fully contain the Rim Fire by September 20.