Search-and-rescue teams have started looking for bodies in parts of California wine country devastated by wildfires as the death toll reached 26.
Some 3,500 homes and businesses have been destroyed by the blazes, which could become the deadliest and most destructive in the US state's history.
Sonoma County Sheriff Robert Giordano said officials were still investigating hundreds of reports of missing people and that recovery teams would soon begin conducting "targeted searches" for specific residents at their last-known addresses.
"We have found bodies almost completely intact and we have found bodies that were nothing more than ash and bones," Mr Giordano said.
Some remains have been identified using medical devices that turned up in the scorched heaps that were once homes.
Metal implants, such as artificial hips, have ID numbers that helped identify the person, he said.
Winds of up to 45mph were expected in areas north of San Francisco and stronger, more erratic gusts were forecast for Friday. Those conditions could erase modest gains made by firefighters.
"We are not out of this emergency. We are not even close to being out of this emergency," emergency operations director Mark Ghilarducci said.
More than 8,000 firefighters were battling the blazes and more manpower and equipment was pouring in from across the country and from as far as Australia and Canada, officials said.
The ferocious fires that started on Sunday levelled entire residential areas in parts of Sonoma and Napa counties.
In anticipation of the next round of flames, entire cities evacuated, leaving their streets empty, the only motion coming from ashes falling like snowflakes.
Fire officials are investigating whether downed power lines or other utility failures could have sparked the fires.
An estimated 25,000 people have been driven from their homes by the flames, including the entire community of Calistoga, a historic resort town known for wine tastings and hot springs with a population of 5,300.
As the wildfires raged for a fourth day, they continued to grow in size.
A total count of 22 fires on Wednesday grew to 21 on Thursday because two large fires had merged together, said state Fire Chief Ken Pimlott.
Many burned out of control. The flames spanned more than 300 sq miles, an area equivalent to the size of New York City's five boroughs.
Fire crews reported some progress on a blaze burning in Napa and Sonoma counties, the heart of wine country.
The ash rained down on Sonoma Valley, covering windshields, as winds picked up.
Helicopters and air tankers assisted thousands of firefighters who were trying to beat back the flames.
Until now, the efforts have focused on lives and safety rather than extinguishing the blazes, partly because the flames were shifting with the wind and targeting communities without warning.