A searing heat wave is fueling at least a dozen wildfires across the West and has killed at least six people, officials say.
Of particular concern are two new wildfires sparked Monday in the San Gabriel Mountains near Los Angeles. More than 800 residents were evacuated in the city of Azusa and parts of Duarte, while others were under voluntary evacuations.
Smoke clouded the sky for miles from the fires, which were burning less than 2 miles apart. One fire was sparked by a deadly car accident, according to the California Highway Patrol. The cause of the other wasn't yet known.
The fires have scorched more than 7 square miles. Fire authorities on Tuesday said they are treating both fires as a single incident called the San Gabriel Complex. The blaze was 10 percent contained Tuesday night.
Chief Robert Garcia of the Angeles National Forest told NBC Los Angeles the fires are in areas of the forest that "have not burned in a number of years."
Complicating the efforts to beat back the fires: Brutal heat that has put nearly 9 million people under heat alerts in the West and Southwest on Tuesday.
Temperatures were expected to be slightly cooler than the inferno a day before. In Palm Springs, California, the mercury rose to 123 degrees on Monday — a new daily record. In Phoenix, temperatures hit 115 degrees — hot enough to fry an egg on pavement, residents pointed out on social media.
Death Valley, California, registered the hottest temperatures in the country at 126 degrees Monday.
Temperatures were forecast to reach 110 degrees Tuesday afternoon in Azusa, the site of one of the growing wildfires, said weather.com meteorologist Brian Donegan.
"Both the heat and the breeze are helping spread the fire. Gusts could still be around 15 mph overnight, but tomorrow the winds should diminish to 5-10 mph," he said.
There was a glimmer of hope elsewhere. A nearly week-old blaze in the rugged mountains west of Santa Barbara, the so-called Sherpa Fire, was 70 percent contained by Tuesday, an increase from 62 percent containment Monday night, officials said.
Most mandatory evacuations in the Sherpa Fire would be lifted Wednesday morning, and nearly all would be over by Saturday, authorities said Monday night. Nearly 8,000 acres, or more than 12 square miles, have burned.
At least six deaths have been attributed to the weather. Four hikers died in separate incidents in Arizona over the weekend, authorities said Sunday. On Monday, a fifth hiker who had gone missing was confirmed dead. On Tuesday, a hiker that had been reported missing in Ventana Canyon was found dead, the Pima County Sheriff's Office said.
"It really shows how critical this heat can be and how it can really sneak up on you," Captain Larry Subervi, a Phoenix Fire spokesman, told The Arizona Republic. "When we deal with temperatures like this, it can just really be unpredictable how your body is going to respond."
Meanwhile, another California wildfire near the Mexican border exploded in growth, swelling from nearly 3 square miles Monday morning to more than 11 square miles by Tuesday morning, the California Department of Forestry and Fire Protection said.
Five percent of the blaze near Potrero, California, a desert town by the Mexican border, was contained Tuesday. Mandatory evacuation orders were expanded Tuesday. Hundreds were forced to leave their homes as the fire spread, according to NBC San Diego.
Three firefighters suffered heat-related injuries, The Associated Press reported. Four structures have been destroyed, but 800 more were threatened.
There were also blazes burning across Arizona and New Mexico. A 28-square-mile fire that erupted last week destroyed 24 homes in the Manzano Mountains south of Albuquerque, but by Tuesday the blaze was 46 percent contained.
In eastern Arizona, a fire on the Fort Apache Indian Reservation southwest of Show Low grew from nearly 42 square miles to 56 square miles from Monday ton Tuesday. The fire was 20 percent contained Tuesday afternoon.
The scorching temperatures weren't expected to drop for days.
"We don't really see much relief until we get into the weekend," TODAY meteorologist Al Roker said.