CLOVIS, Calif. (KFSN) -- The Rough Fire east of Fresno in the Sierra National Forest is expected to eventually burn between 30,000 and 40,000 acres.
Officials with the U.S. Forest Service say the fire jumped the middle fork of the Kings River yesterday, increasing the size of the fire tonight to more than 12,000 acres.
Around 200 firefighters with the forest service are dealing with incredibly steep terrain, which not only poses a safety issue, but makes the fire difficult to contain.
So they're relying on historic fire lines from previous wildfires and the area's natural terrain to help them fight it.
"We're trying to fight the fire on our own terms so we use natural barriers where possible, rock features, meadows, lakes rivers, and that really assists us in creation of the fire line," said U.S. Forest Service Deputy Chief Van Arroyo.
Firefighters are concerned that the fire could jump to the south side of the Kings River, which could threaten three giant sequoia groves and Hume Lake Christian Camp.