A brush fire in a mountainous area north of Los Angeles ignited and spread quickly Thursday, forcing thousands of evacuations.

Fire officials say the blaze is threatening power lines as well as the communities of Hasley Canyon and Hathaway Ranch.

Temperatures in the area are near 100 degrees and humidity as low as 15 percent. The southern part of California has seen very little rain, drying out vegetation and making it "ripe to burn," the National Weather Service (NWS) for Los Angeles warned.