California's latest wildfire mushroomed into an inferno covering more than 120 square kilometers (46 square miles) in just a day, the National Wildfire Coordinating Group said on Wednesday.

The fast spread of the so-called "Blue Cut" fire led to a mandatory evacuation order for at least 82,000 people due to what authorities described as an "imminent threat to public safety, rail traffic and structures."

"I have 17 to 18 people staying at my house now, friends and their families that have had to evacuate from Wrightwood," resident of the town of Pinon Hills, Jeannine Yglesia, told the AFP news agency. "They cannot go back and don't know about their house."

More than 1,300 firefighters were battling the fire, utilizing air tankers and helicopters to sweep over the flames from the sky. Local media showed footage of "firenadoes" - tornado-like flaming vortices - that were sent spinning into the air by the sheer strength of the blaze.

The newest fire also closed several roads including a major interstate highway linking Los Angeles and Las Vegas.

California Governor Jerry Brown declared a state of emergency for San Bernardino County, just 100 kilometers (60 miles) east of Los Angeles, saying the blaze was too big for the region to fight alone.

Emergency teams have been battling wildfires throughout California over the past three months, amid a historic drought, and as NASA revealed that July was the 10th month in a row to break the monthly temperature record, becoming the hottest month since records began in 1880.

Louisiana assesses damage

Meanwhile, a huge clean up operation got underway in the southern US state of Louisiana on Wednesday, as severe floods receded after a deluge that lasted several days.

Residents around the city of Baton Rouge returned to their homes to assess the damage and get to work on repairs, while thousands more waited in case swollen rivers caused further flooding in the coming days.

The American Red Cross described the flooding, which claimed 11 lives and damaged some 40,000 homes, as the worst natural disaster since Hurricane Sandy in 2012.

"I can't even think about what to do, just have to go with it as it comes in," James Lane, a resident of the town of Sorrento said. "We actually lost everything in Katrina, came here 10 years later, lost everything again."

Officials said the number of residents staying in shelters had fallen by almost half since 11,000 people were moved earlier this week.

The Red Cross launched a donation campaign and deployed 67 emergency response vehicles, telling local media that thousands of its staff and volunteers were due to arrive.

Louisiana Governor John Bel Edwards described the flooding as "unprecedented" and called on residents to register for federal disaster relief.

Edwards requested that 21 parishes be included in the federal government's major disaster declaration, which will make thousands more residents eligible for compensation.

mm/sms (AFP, AP, dpa, Reuters)