The Ponderosa Fire is currently 50 percent contained. At first, about 3,500 homes were threatened, but that number has been lowered to roughly 200.
"There's still work to be done, but good progress is definitely being made," CalFire spokesman Daniel Berlant said.
The blaze has scorched some 38 square miles since it was sparked by lightning on Saturday. More than 2,100 firefighters were battling the fire near the remote towns of Shingletown, Manton and Viola, about 170 miles north of Sacramento.
California Gov. Jerry Brown announced Tuesday that National Guard troops will be assisting with the firefighting efforts. The news comes a day after the Federal Emergency Management Agency said it is offering federal funds to help cover the cost.
Another massive wildfire burning in Plumas National Forest continues to grow due to gusty winds. The fire has scorched nearly 98 square miles since it started at the end of July. About 900 homes are threatened. Officials said Wednesday that it was 37 percent contained.
In Mendocino County, a wildfire has forced mandatory evacuations for residents in Covelo. That wildfire has burned more than 18 square miles.
The Associated Press contributed to this report.