Electricity firm Southern California Edison reported to regulators that it was investigating whether its equipment might have sparked the Silverado Fire near the city of Irvine.
Some of the biggest wildfires California has seen in living memory are continuing to tear through the north of the state, as firefighters battle the flames in a bid to save homes and lives.
"The fierce struggle will continue throughout the night to bring the population to safety and protect homes," the fire service said on Twitter.
The Australian outback town of Broken Hill was blanketed in dust as storms swept over parts of the New South Wales state on Wednesday.
Bad weather brought chaos to parts of Australia, in the form of giant hailstones that pounded the capital Canberra. The storm brought down trees, caused flash flooding and inflicted minor injuries on residents.
The fires have been unprecedented.
Wildfires ravaging Australia have taken a grisly toll on the country's wildlife with hundreds of millions of wild animals believed to have been killed in the blazes, along with thousands of livestock.
Grisly images from New South Wales show the remains of animals at the roadside in Batlow where a man also died defending his property from the out of control bushfires.
Thousands of tourists fled Australia's wildfire-ravaged eastern coast Thursday ahead of worsening conditions
A giant wall of smoke and flames hovers over the Melbourne suburb of Cranbourne, as Australia endures one of the worst days of its months-long bushfire crisis.