The Mosquito Fire burning in the mountains west of Lake Tahoe has burned 41,433 acres in four days, according to Cal Fire.
On Sunday, officials said the fire was 10% contained.
Residents of Foresthill, Michigan Bluff, and other communities in parts of Placer and El Dorado counties have been ordered to leave their homes. Cal Fire estimates that 3,666 buildings are threatened by the flames.
For detailed evacuation information, check Cal Fire's website.
The fire broke out Tuesday. The cause is under investigation.
However, Pacific Gas & Electric revealed that crews from the national Forest Service cordoned off one of the power poles owned by the utility near where the fire ignited.
PG&E says it has not been told why the pole is surrounded by yellow tape and it has not seen any problems with that piece of equipment.
Mountainous terrain and daily temperatures of 100 degrees or more have hindered attempts by firefighters to control the inferno.
"This canyon, the three forks of the American River, and the Rubicon drainage are three of the most unforgiven pieces of country we have in Northern California," said Brian Estes, Placer County's fire chief.
Another large wildfire is burning in Southern California. The Fairview Fire has killed two people in Hemet as it burned through more than 28,307 acres. That fire is 40% contained.