At least two victims had to be taken to hospital by helicopter after the blaze, dubbed Caldor Fire, devastated a small town about 80 km from Sacramento in the state's north.
Thousands of residents were preparing to flee the advancing flames that have ravaged the Eldorado National Forest since August 14, thanks to extreme drought and sustained winds.
"Please, please listen to the warnings, and when you are asked to evacuate, go!" Pleaded California Fire Chief Thom Porter, as quoted by the Sacramento Bee newspaper. .
"We need you not to be in our paws to be able to protect your homes from these fires," he insisted.
The fire increased its surface area eightfold in the space of 24 hours and was not at all contained Wednesday morning, according to the latest report established by the firefighters.
Air quality alert
Images taken by an AFP photographer bear witness to the height of the flames engulfing the trees along a road where firefighters are trying to stop their progress.
Too late for the small town of Janesville, lined with charred car wrecks.
Thick fumes from the multiple forest fires triggered an air quality alert for residents of the San Francisco area, while energy supplier PG&E had to cut power to some 50,000 customers on Tuesday. .
The operator, blamed for the Dixie Fire, explained that this measure was intended to prevent power lines from causing new fires if they fell on dry vegetation like straw.
The number and intensity of forest fires have increased in recent years in the western United States, with a marked extension of the fire season.
According to experts, this phenomenon is particularly linked to global warming: the increase in temperature, the increase in heat waves and the drop in precipitation in places form an ideal incendiary cocktail.
Planet
United States: The "Dixie Fire", the 2nd largest fire in California history, continues its mad course
World
United States: Firefighters annoyed by endless fires in California
California
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Fire