Firefighters battled wind-whipped wildfires Tuesday in California which have left at least 11 people dead , thousands homeless and ravaged the state's famed wine country .

California Governor Jerry Brown declared a state of emergency in three northern counties -- Napa, Sonoma, and Yuba -- and said thousands of firefighters had been deployed to fight the blazes.

Seven deaths were reported in Sonoma County, two in Napa County, one in Yuba County and one in Mendocino County and the governor said "emergency responders anticipate the number of fatalities could grow."

Among the dead in Napa were a couple aged 99 and 100 years old who had been married for 75 years, KTVU-TV said. They were unable to evacuate their home in time.

The fires have burned more than 100,000 acres (40,500 hectares), forced the evacuation of more than 20,000 people and destroyed over 2,000 homes and businesses, according to the authorities.

Appealing Monday to President Donald Trump for federal aid, Brown said at least 18 fires had broken out in seven counties.

"These fires have been extremely difficult to contain and many remain at zero percent containment," he said. "The devastation and disruption caused by these fires is extraordinary.

"Thousands have been made homeless ."

'Boom, boom, boom'

Troy Newton, 46, a Sonoma County sheriff's detective, told The Los Angeles Times he was returning to his home in the Santa Rosa neighborhood when he saw a "growing red snake" of fire.

"I ran into my house and told my wife to get our four-year-old boy ready to leave," Newton said, before raising the alarm with around 40 neighbors.

"It was boom, boom, boom. Ring the door bell. Boom, boom -- until someone inside got the message," he said.

Ken Pimlott, director of the California Department of Forestry and Fire Protection (CalFire), said the fires were being spread by 50- to 60-mile per hour (80-100 kilometer per hour) winds.

Many homes in Santa Rosa, the county seat of Sonoma, were razed to the ground and the Hilton Sonoma County Wine Hotel, Fountaingrove Inn and Willi's Wine Bar reportedly suffered damage.

The Hilton Hotel in Santa Rosa said on Facebook that its staff and guests were all safe. The Los Angeles Times said hundreds of patients at two Santa Rosa hospitals had also been evacuated safely.

Among the wineries which reportedly suffered damage were William Hill Estate Winery in Napa, Signorello Vineyards, Stags' Leap and Chimney Rock.

Coffey Park, a sprawling Santa Rosa neighborhood with dozens of homes, was left in ruins.

Cheri Sharp told Oregon-based TV news channel KOBI her home of 26 years in Santa Rosa was among those destroyed.

"All our pictures are gone. Everything, everything is gone," she said.

"We're all healthy and safe, and we have to try and be grateful for that. But it's pretty awful."

Drought declared over in April

Pacific Gas & Electric said more than 196,000 customers had initially lost electricity although half had had their power restored.

Marian Williams of Kenwood, in Sonoma County, told NBC Bay Area she joined a convoy of neighbors driving through the flames before dawn as one of the fires reached the area's vineyards.

"It was an inferno like you've never seen before," Williams told the station.

Governor Brown in April declared the official end of the state's drought that lasted more than five years.

But California is still dealing with the Santa Ana winds, a meteorological phenomenon which brings dry winds down from the high mountains east of the coastal areas -- a recipe for perfect wildfire conditions.

Forest fires are common in the western United States during dry, hot summer months.

Last month, a massive fire described as the biggest in the history of Los Angeles forced hundreds to evacuate their homes.