Los Angeles is surrounded by fire.

The city’s major wildfires have spread, and a new one started overnight in Hollywood Hills. It threatened a wealthy neighborhood and landmarks synonymous with America’s self-image — the Hollywood sign, the Walk of Fame. Streets near Hollywood filled with traffic as helicopters raced through the sky. (Track the fires with these maps.)

The wildfires have killed at least five people; forced tens of thousands to evacuate; and charred entire neighborhoods of every socioeconomic status, from the scenic West Coast to the inland suburbs. “It wasn’t just that the place was in flames. It was that it seemed to be in flames everywhere at once,” The Times’s Shawn Hubler wrote of the city.

Below, we explain how these fires became a major crisis so quickly.

While Southern Californians are used to wildfire, these blazes are a shock in three key ways:

• Location: Wildfires are normally contained to Southern California’s dry hills. These fires have burned out of control and spread into the city, and two are the most destructive in Los Angeles’s history. The flames are visible for miles down the city’s famous coastline, a half-moon crescent of sand that is usually domed by blue sky. “I’ve lived here my whole life and never seen anything like this,” a 71-year-old resident said.
• Extreme winds: Intense winds, known as Santa Anas, have spread these fires into the city. The winds also made it unsafe for aircraft to douse the flames from above, which slowed firefighting. Santa Anas are notorious for aiding California wildfires in the fall, after the landscape dries in the summer. But the impact is often less dramatic by winter, when the hills are more moist from rain. That hasn’t been true this year.
• Dry conditions: It hasn’t rained much in Los Angeles for months. As a result, the fires spread more quickly across a dry landscape. Water supplies were also limited. Firefighters sprayed water faster than tanks could be refilled, and hydrants ran dry. Some residents stood and watched as their homes burned away. On Sunset Boulevard, one man fell to his knees and begged firefighters to save his house. Without water, they were helpless to stop the flames.

In Altadena, Calif.Credit…Kyle Grillot for The New York Times

Firefighters are continuing their battle, but more destruction is expected.

President Biden canceled a trip to Italy, in which he was supposed to meet the Pope, to coordinate the federal response to the wildfires. The White House said it had arranged for Navy helicopters to join the firefighting effort.

Biden also appeared alongside Gavin Newsom, California’s governor, at a fire station in Santa Monica. “We’re prepared to do anything and everything, as long as it takes, to contain these fires and help reconstruct, make sure we get back to normal,” Biden said.

Forecasters warned that extreme fire danger would continue for at least another day, and millions of people in Southern California remain under fire warnings — which have heightened anxiety across the region.

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