California was lashed by powerful winds on Wednesday that fed a fast-moving wildfire, which destroyed dozens of homes and forced thousands of residents to flee as forecasters warned of the potential for "extreme and life-threatening" blazes.
Northwest of Los Angeles, the Mountain Fire exploded in size and prompted evacuation orders for more than 10,000 people as it threatened 3,500 structures in suburban communities, ranches and agricultural areas around Camarillo, according to a statement from Governor Gavin Newsom.
The area east of the Pacific coast city of Ventura will receive federal assistance after a request from Mr Newsom was granted, the Federal Emergency Management Agency said.
The blaze was burning in a region that has seen some of California's most destructive fires over the years. A thick plume of smoke rose hundreds of feet into the sky on Wednesday, blanketing whole neighbourhoods and limiting visibility for firefighters and evacuees.
The fire grew from less than half of a square mile to 16 square miles (62 square kilometres) in little more than five hours.
Ventura County fire captain Trevor Johnson described crews racing with their engines to homes threatened by the flames to save lives.
"This is as intense as it gets. The hair on the back of the firefighters' neck I'm sure was standing up," he said during a news conference on Wednesday afternoon.
At one spot, flames licked the burning remains of a home. Its roof was reduced to only a few charred shingles.
Two people suffered apparent smoke inhalation and were taken to hospitals, fire officials said. No firefighters reported significant injuries.
The erratic winds and limited visibility grounded fixed-wing aircraft, and gusts topped 61 mph (98 kph), said weather service meteorologist Bryan Lewis. Water-dropping helicopters were still flying.
First responders pleaded with residents to evacuate. Deputies made contact with 14,000 people to urge them to leave as embers spread up to 2.5 miles (4 kilometres) away and sparked new flames.
"This fire is moving dangerously fast," Ventura County fire chief Dustin Gardner said.
Aerial footage from local television networks showed dozens of homes in flames across several neighbourhoods as embers were whipped from home to home. Other footage captured horses trotting alongside evacuating vehicles.
Officials said they were using all resources, including water-dropping helicopters and fixed-wing aircraft dropping fire retardant, but it was still burning out of control on Wednesday afternoon.
Andrew Dowd, a Ventura County fire spokesperson, said he did not have details of how many structures had been damaged.
Meanwhile to the south, Los Angeles County Fire Department crews scrambled to contain a wildfire near Malibu's Broad Beach as authorities briefly shut down the Pacific Coast Highway as flames burned near multimillion-dollar properties.
Residents were urged to shelter in place while aircraft dropped water on the 50-acre (20-hectare) Broad Fire. It was 15% contained around 12.30pm with forward progress stopped. Fire officials said two structures burned.
The National Weather Service office for the Los Angeles area amended its red flag warning for increased fire danger with a rare "particularly dangerous situation" label, and officials in several counties urged residents to be on watch for fast-spreading blazes, power outages and downed trees amid the latest round of notorious Santa Ana winds.
With predicted gusts between 50mph (80kph) and 100mph (160kph) and humidity levels as low as 8%, parts of Southern California could experience conditions ripe for "extreme and life-threatening" fire behaviour into Thursday, the weather service said.
Forecasters also issued red flag warnings until Thursday from California's central coast through the San Francisco Bay Area and into counties to the north, where strong winds were also expected.
Utilities in California began powering down equipment during high winds and extreme fire danger after a series of massive and deadly wildfires in recent years were sparked by electrical lines and other infrastructure. On Wednesday, more than 65,000 customers in Southern California were without power preventatively, and upwards of 20,000 in Northern California.
