Newsom says California battling 560 wildfires

California's lightning-sparked wildfires more than doubled in size into some of the largest in state history on Friday, with one blaze advancing to within a mile of the University of California Santa Cruz.

At least six people have died, 43 fire fighters and civilians have been injured, and over 500 homes and other structures destroyed as fires have burned an area larger than the U.S. state of Rhode Island.

Firefighting forces were depleted as they fought the blazes. Only 45 of 375 out-of-state fire crews requested by California had arrived, said a spokeswoman for wildfire authority Cal Fire.

The state has been hit by its worst dry-lightning storms in nearly two decades. Close to 12,000 strikes have sent fire racing through lands parched by record-breaking heat, forcing 175,000 to evacuate their homes, largely in Northern California.

The lightning strikes, driven by record temperatures, were a consequence of climate change and more such storms are expected on Sunday, Newsom said.