Powerful winds were fanning wildfires in northern California in “potentially historic fire” conditions, authorities said Sunday, as tens of thousands of people were ordered to evacuate and sweeping power cuts began in the US state.

Gusts of 80 miles per hour (130 kph) were fueling the Kincade blaze—which threatens tens of thousands of structures—causing it to burn with greater intensity in remote steep terrain north of San Francisco, the National Weather Service said.

The Sonoma County Sheriff’s office early Sunday issued an evacuation warning for much of the city of Santa Rosa, which has a population of some 180,000 people.

Nearly 90,000 people were ordered to flee their homes on Saturday as the Sonoma county fire spread after breaking out midweek. A total of 77 structures, including 31 residential buildings, had been destroyed by the blaze on Saturday, as more than 2,800 personnel were called to the scene, according to Jonathan Cox, spokesman for the California Department of Forestry and Fire Protection.