Thousands more residents evacuated their homes Saturday as wind gusts threatened to spread destructive wildfires that have killed at least 40 people in California's wine country over the past week.

Firefighters are battling 17 wildfires that have turned 86,000 hectares (214,000 acres) of Sonoma County into a burnt wasteland, with at least 5,700 homes and businesses charred to the ground. 

Williams Chalmers is one Santa Rosa resident who received a knock on his door from firemen in the pre-dawn hours of Friday morning telling him he had to leave his home immediately.

"We are safe," he said of himself and his wife, child and dog in a phone interview with DW. "We are running for our lives." Chalmers has had no news of his home since fleeing.

Evacuations continue

After reporting progress in containing the wildfires on Friday, authorities ordered 400 homes to evacuate in Sonoma early Saturday after rising winds fanned flames near the town of about 11,000 people. So far, at least 100,000 people in northern California have been evacuated from their homes in the past week. Chalmers described roads packed with cars as people fled. 

The fires have been fed by dry weather and winds, with gusts of up to 64 kilometers per hour (40 miles per hour) reported on Saturday. The winds have sent loose embers over hastily constructed barriers and large distances, spreading the fire into Sonoma and other areas, and causing blazes to merge and disperse. 

The winds are "testing the work that we accomplished," said Daniel Berlant, a spokesman for the California Department of Forestry and Fire Protection.

Despite having been prepared to evacuate over the past few days, Chalmers described the abrupt change from feeling safe with fire officials nearby to suddenly being in danger and being told to leave. In his case, an wind-borne ember started a 300-acre fire "not to far from where my house was — is, hopefully," he said.

"It's an unwieldy beast right now," said Dennis Rein, fire information officer at the Sonoma County Fairgrounds in Santa Rosa.

In total, some 10,000 firefighters, including many from out of state, have been deployed to battle the wildfires, with air tankers and helicopters dumping retardant. Firefighters have also spent the last week digging trenches and clearing brush to stop the spread of the state's deadliest-ever wildfires.

 Read more: How climate change is increasing forest fires around the world 

'Absolute gray destruction'

In Santa Rosa, the hardest hit town, whole neighborhoods have been burnt to the ground. Chalmers described a scene of total devastation in the area where he lives. 

"It is a war zone. It is a moonscape of absolute gray destruction. The only thing standing from people's whole lives are chimneys," he said. "On the other hand, it is equal opportunity. It is laying waste to trailer homes, housing developments, mountain top mansions, wineries, ranches, parks, schools. Needless to say, to people's lives."

More than 200 people are still missing. Officials fear the death toll may rise as they search through the thousands of scorched homes and vehicles for the remains of individuals who did not have time to flee the sudden eruption of flames near their homes.

"They are finding skulls and bones and identifying people by their hip replacement or their knee replacement identification number," Chalmers said of the search efforts. "That is all that is left of people who had a minute's notice of the fire and were probably engulfed."

Phone interview by Andy Valvur