California fires: Thirteen dead in wine country

At least 13 people have now died in fast-spreading fires that are ravaging parts of California's wine region.

A state of emergency was declared in northern areas after mass evacuations, with 2,000 structures destroyed.

About 20,000 people fled from Napa, Sonoma and Yuba counties in response to some the state's worst-ever wildfires.

Such fires are more common in southern California but a combination of dry weather and strong winds has fuelled the destruction in the north.

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Cal Fire officials said on Tuesday morning that 17 wildfires in nine counties have burned more than 115,000 acres in just the past 12 hours.

Fifteen fires were burning across eight Californian counties

"These fires have destroyed structures and continue to threaten thousands of homes, necessitating the evacuation of thousands of residents," Governor Jerry Brown said.

President Donald Trump has approved a disaster declaration for the fire-ravaged state, allowing federal emergency aid to be sent.

There is little sign the weather in the coming days will bring much relief to firefighters, BBC Weather says. More tinder dry conditions are forecast, with no rain expected.

Meanwhile, in southern California, a separate wildfire burnt 24 homes or other buildings in the wealthy Anaheim Hills area of Orange County, forcing thousands of residents to evacuate.

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What do we know of the loss of life and damage?

The fires - considered among the deadliest in state history - have sent smoke as far south as San Francisco, located about 60 miles (96km) away.

A new fire is reportedly burning near the Oakmont area of Santa Rosa, a city that has already been devastated by the blazes.

Hundreds of homes have been destroyed in the city by flames so hot that glass melted on cars.

Details of how the seven people died in Sonoma were not immediately available, but country sheriff Rob Giordano said he expected the death toll to rise.

"There is a lot of burned homes and a lot of burned areas, so it's just logical that we're gonna find more people," he said.

Two people also died in Napa county and one in Mendocino county when thousands of acres burned in one valley.

Sonoma County officials said they had received more than 150 missing-person reports by Tuesday.

Authorities said they have found a few of the missing persons but most of the reports were still under investigation, Sonoma County spokesman Scott Alonso said.

Dozens of vineyard workers were reportedly airlifted to safety overnight.

Wineries belonging to the rich and famous were abandoned. One belonging to musician Dave Matthews was closed and at risk of being burned to the ground, staff said, as was the nearby Francis Ford Coppola Winery.

The vine harvest is already under way and many of the grapes have been picked.

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Why did the fires spread so fast?

It is not yet known how the fires started on Sunday night but such blazes are particularly fast-spreading because of a combination of 60mph 96km/h) winds, low humidity and hot, dry weather.

Officials say at least one person has died and about 1,500 buildings have been destroyed overnight

Ken Moholt-Siebert, a vineyard owner who thought his property had probably been destroyed after he and his family escaped on Sunday night, described the suddenness of the disaster.

"There was no wind, then there would be a rush of wind and it would stop. Then there would be another gust from a different direction. The flames wrapped around us," he told the LA Times.

The fires come in a year of record-setting heat and persistent drought, according to the San Francisco Chronicle.

Why are these fires unusual?

The combination of conditions is more typical of southern California, the LA Times reports.

"This is exactly what you would expect in the Southern California fall fire season," Cal Fire director Ken Pimlott said.

Hundreds of homes have been destroyed in the wildfires

Valerie Schropp, a resident of Santa Rosa, which was badly affected by the fire, told the BBC they had never seen anything like this before.

"We don't expect fires to come into the city and burn at the rate they did," she said.