The Palisades fire between Santa Monica and Malibu on the city's western flank and the Eaton Fire in the east near Pasadena are already the most destructive in Los Angeles history, turning entire neighbourhoods to ash.
Swathes of the United States' second-largest city lay in ruins, with smoke blanketing the sky and an acrid smell pervading almost every building.
At least five people have been killed, thousands of structures have been incinerated and nearly 180,000 people have been ordered to evacuate their homes, officials said.
Among those who died was 66-year-old Victor Shaw, whose sister said he had ignored pleas to leave as the fire swept through Altadena because he wanted to protect their home.
"When I went back in and yelled out his name, he didn't reply," Shari Shaw said.
"I had to get out because the embers were so big and flying like a firestorm that I had to save myself."
Shaw's body was found by a friend on the driveway of his razed home, a garden hose in his hand.
The two biggest conflagrations - the Palisades and Eaton fires - formed a pincer around the city so enormous that it was visible from space.
The homes of movie stars and celebrities were among those consumed by flames, which tore through some of the world's most lavish real estate.
"We are heartbroken of course, but with the love of children and friends we will get through this," said film star Billy Crystal and his wife Janice, announcing that the Pacific Palisades home where they had lived since 1979 had been destroyed.
Media personality Paris Hilton said she was "heartbroken beyond words" after watching her beachfront house in Malibu "burn to the ground on live TV."
The fires struck at an especially vulnerable time for Southern California, which has not seen significant rainfall for months. Then came the powerful Santa Ana winds, bringing dry desert air from the east toward the coastal mountains, fanning wildfires while blowing over the hilltops and down through the canyons.
Wind gusts were expected to strengthen on Thursday evening through to Friday morning, with another round of strong winds expected early next week, raising concerns that the conditions could worsen, the National Weather Service said.
At least 20 arrests have been made for looting, and the city of Santa Monica declared a curfew on Wednesday night because of the lawlessness, officials said.
Los Angeles County Sheriff Robert Luna said to protect properties, national guard troops would be stationed near the areas ravaged by fire and a curfew was expected to go into effect from 6 pm until 6 am, starting as soon as Thursday. (Agencies)
