Thousands of people fled their homes in northern California on Wednesday as hundreds of fast-moving wildfires spread across the region, burning houses and leading to the death of a helicopter pilot.

In Vacaville - a city of about 100,000 people located between the state capital Sacramento and San Francisco - residents were urged to evacuate during the night as the wind-whipped flames swallowed dozens of homes.

Many were awakened by neighbors or firefighters desperately banging on their doors, and rushed out dressed only in their pajamas. 

Several suffered burns as they ran for their lives.

Evacuation orders or warnings were also issued in other counties - including the wine regions of Sonoma and Napa - where fires sparked by lightning are raging unchecked amid a sweltering heat wave.

Cal Fire officials said the series of fires in that region, dubbed the LNU Lightning Complex, had destroyed 50 homes, burned through nearly 50,000 acres and were zero percent contained by early Wednesday evening.

AFP