At least 5 people killed in Northern California wildfires

Dozens of wildfires raging throughout Northern California have now claimed at least five lives and threaten tens of thousands of homes, authorities said Thursday.

The death of a resident in Solano County, in the northeastern San Francisco Bay Area, was reported Thursday by Sheriff Thomas A. Ferrara, although he didn't have any additional details.

In addition, three civilians had died in Napa County since the fires began, said Daniel Berlant, a Cal Fire assistant deputy director. In all, more than 30 civilians and firefighters have been injured.

It wasn't immediately clear whether the Solano and Napa county fatalities included a Pacific Gas & Electric utility worker who was found dead Wednesday in a vehicle in the Vacaville area between San Francisco and Sacramento.

A pilot on a water-dropping mission in central California also died Wednesday when his helicopter crashed.

Gov. Gavin Newsom addressed the wildfires, calling them clear evidence of climate change, in a last-minute video recorded for the Democratic National Convention from a forest near Watsonville after he visited an evacuation centre.

"If you are in denial about climate change, come to California," he said.

"I confess this is not where I expected to be speaking here tonight," he said into what appeared to be a cellphone camera. Newsom had recorded an earlier, more lighthearted video, to be delivered in the convention's prime-time hours but decided it didn't bring the right tone amid his state's disasters, said Dan Newman, one of his political advisers.

More than two dozen major fires were scorching California and taxing the state's firefighting capacity, sparked by an unprecedented lightning siege that dropped nearly 11,000 strikes over several days.

More than 30 injured, 2 missing

The fires have destroyed 175 structures, including homes, and are threatening 50,000 more, said Daniel Berlant, an assistant deputy director with the state Department of Forestry and Fire Protection. In all, 33 civilians and firefighters have been injured.

At least two people were missing.

Smoke and ash billowing from the fires has fouled the air throughout the scenic central coast and San Francisco.

Most of the activity is in Northern California, where fires have chewed through about 1,250 square kilometres of brushland, rural areas, canyon country and dense forest surrounding San Francisco.

More than 10,000 firefighters are on the front lines, but fire officials in charge of each of the major fire complexes say they are strapped for resources. Some firefighters were working 72-hour shifts instead of the usual 24 hours. The state has requested 375 engines and crew from other states.

Fire officials said the flames were being driven by bone-dry timber and brush and erratic winds. They pleaded with residents to be ready to evacuate when ordered because they place firefighters in danger when crews have to protect those staying behind.

In Marin County, just north of San Francisco, where a smaller fire is burning near the Pacific Ocean, county fire chief Jason Weber said he is waiting for assistance from Montana to arrive this weekend.

He said in his 25 years in fire service, "we've never seen this level of draw-down" from cooperating agencies, as there is heavy competition in the western United States for equipment and people.

In the coastal mountain regions south of San Francisco, where 48,000 people were under orders to evacuate, a fire complex had burned 194 square kilometres. Officials warned it has the potential to grow significantly in the next day.

At least 50 buildings, including homes, had burned and nearly 21,000 structures were threatened, fire officials said.