GRIZZLY FLATS, Calif. (AP) — Northern California wildfires that incinerated two mountain communities continue to march through the Sierra Nevada and the Pacific Gas & Electric utility is blacking out some 51,000 customers to prevent new blazes.

The Dixie Fire that ravaged much of the small community of Greenville two weeks ago was still threatening others Wednesday. And the Caldor Fire to the south burned at least 50 homes as it ravaged the small town of Grizzly Flats.

Hot, dry and gusty weather is driving flames through tinder-dry vegetation.

The utility on Tuesday began shutting down power to parts of 18 northern counties to prevent winds from damaging power lines and sparking new fires.