One week after the Palisades Fire rushed down a mountainside, swallowing whole communities and killing at least eight people, its cause remains unknown.
The answers, when they emerge, will most likely be found on a scorched and blackened ridgeline in western Los Angeles overlooking a Pacific Palisades neighborhood that includes a popular hiking trail — an area that was also the scene of a small fire six days earlier.
Understanding the catastrophic Jan. 7 fire could take months, a process that began with investigators collecting videos and photographs from nearby homes and social media, interviewing witnesses and firefighters and examining 911 calls, looking for leads.
“All of this is going to take time,” Jose Medina, acting special agent in charge of the Bureau of Alcohol, Tobacco, Firearms and Explosives’ Los Angeles office, said at a news conference Tuesday. He said there were 75 federal and local investigators on the case. “We know everyone wants answers, and the community deserves answers. ATF will give you those answers, but it will be once we complete a thorough investigation. We have no timeline on when this will occur.”
Investigators haven’t reached any conclusions, though an early focus of the probe has been on potential human causes, according to multiple law enforcement sources familiar with the investigation. The possibilities include arson, an accidental spark, fireworks, unauthorized camping activity or a rekindling of an earlier fire extinguished on New Year’s Day, the sources said.
The probe has led investigators into the ash-covered area where the fire was first spotted, hunting for the smallest of clues.
Windblown wildland fires like the Palisades Fire leave “movement patterns” on the plants, trees, grass, rocks and other objects that, to a trained eye, reveal how the flames spread. Marking those signs, the investigators work backward to the suspected start point.
“If you understand how to read those patterns, it becomes quickly evident where the origin of the fire is,” said Ed Nordskog, a retired Los Angeles County sheriff’s fire investigator, who isn’t involved in the Palisades Fire probe.
Investigators try to narrow their search down to an area of about 25 square feet, then turn the spot into a grid of zones about 4 square feet each, Nordskog said. Using magnets, metal detectors and magnifying lenses, they sift for tiny objects — like fragments of molten machinery parts, a match head, glass, remnants of fireworks — that might explain or rule out a potential cause. They may bring in a dog trained to sniff out traces of accelerants. Nearby electrical equipment, like fences or poles, or signs of gas-powered vehicles also guide them. All the while, other investigators talk to witnesses who may have seen something suspicious.
The ATF’s National Response Team is leading a joint investigation with local authorities of the Palisades Fire, as well as other fires that ignited last week across Los Angeles County and, fed by high winds, ripped through mountainsides and neighborhoods, destroying more than 12,000 structures, consuming more than 40,000 acres and killing at least 25 people. Some of the fires are still burning.
The Palisades Fire, which is the largest, could be the most difficult to explain because of the myriad of potential factors, which investigators will have to eliminate on their way to determining a cause.
The theory that the Jan. 1 fire was responsible has drawn the most public speculation.
That brush fire ignited in the area of the ridgeline sometime after midnight, spotted by residents of the nearby Palisades Highlands neighborhood, which is part of Pacific Palisades. Firefighters put it out, and before 5 a.m. it was deemed contained with no structures damaged and no one hurt. The city fire department didn’t report what caused it.
The fire was largely forgotten until six days later.
Around 8:20 a.m. Jan. 7, Darrin Hurwitz set out on his regular hike up a mountainside trail near his home in the Marquez Knolls neighborhood. It was very windy — authorities had already issued an alert that the gusty conditions put Los Angeles at high risk for fires.
An hour into the hike, as he passed a boulder known as Skull Rock, he said, he noticed a swath of charred vegetation and caught a whiff of smoke. Remembering the New Year’s Day fire, Hurwitz said, he didn’t think much of it, assuming that the smell was left over from it — or that he was detecting fires burning somewhere else far away.
Hurwitz, 49, a lawyer, said he stopped about a couple hundred feet from the burn scar and didn’t see any smoke or anything else remarkable. “It wasn’t enough to think there was anything suspicious,” he said. Hours later, his family escaped the fire as it swept through the neighborhood, but their house was destroyed.
By midmorning, a group of trail runners saw flames and smoke near Skull Rock and raced away, taking pictures and videos as they escaped to safety. Residents of Palisades Highlands reported seeing the growing fire from their homes around 10:30 a.m.
Having two fires in roughly the same area six days apart has fueled speculation that the Palisades Fire was triggered by a rekindling of the earlier one. But experts are divided over whether that is a viable explanation. A 2023 wildfire that destroyed the town of Lahaina on the Hawaiian island of Maui was found to have been the result of a rekindling of a smaller fire, though just a few hours separated those fires.
For days or weeks after a fire, embers can lodge somewhere and remain hot — and the roots of trees can burn underground, Nordskog said. This effect is often seen in mountainous forests, and it isn’t common on the coastal brush of the type at Pacific Palisades, he said. But it is possible, he said.
Scott Sweetow, a former ATF fire investigator, said he doubted that happened in this case.
The relatively light vegetation of the Pacific Palisades landscape and the stretch of six days before the second fire ignited made rekindling “unbelievably improbable,” he said.
