Investigators think they know the general area where the fire started, in the hills around Temescal Ridge Trail, but as for how it started there are still multiple options.

One possibility is a fire which happened about a week earlier. It was apparently started by fireworks and was put out by firefighters after it burned 8 acres. But it's possible that some embers were still burning underground. One neighbor who was hiking the area the morning the fire started saw smoke but no flames that morning.

On the morning the Jan. 7 fire ignited, Mr. Giller said he saw what resembled smoke or dust wafting in the area. “It had the appearance of smoke around there, but there were no flames,” he said in an interview. “It just raised a question in my mind. What is it? I was thinking, could this thing still be active? But it seemed unlikely, you know — could there still be smoke from a fire that happened six days ago? That didn’t make sense to me.”

According to the Times, roots and underground organic material can smolder for up to 7 days and be whipped into flames by winds.

The same neighbor saw a group of younger people near the area that morning. They were hanging out near Skull Rock, a landmark close to where the fire started.

Video posted on social media from that morning show one group of young men near Skull Rock, dressed largely in sneakers and athletic shorts, one carrying a portable speaker. Clips posted by one member of the group begin with the men running along a trail next to a rock, with a faint cloud of smoke coming from the hillside above them. The men, still running, express alarm about smelling smoke and then seeing a fire moving quickly toward them...

The man who posted the video initially agreed to speak with The Times, but then stopped responding to messages. His account on X appears to have been removed.

There's no evidence the men were doing anything but hiking. In particular the video, which seems to be gone now, didn't show any of them smoking. So maybe it was just a coincidence they were there when the fire broke out.

Yet another possibility is that the fire was sparked by power lines. The nearest power lines are uphill about 1/3 of a mile away. They are mostly burned now but the Times found photographs showing they were still standing when the fire started burning. In other words, they appear to have been burned as the fire climbed the hill from the ignition point. In any case, there was a plan to replace these wooden power poles, put in place in the 1930s, with metal ones but it got derailed by environmentalists.

...the Los Angeles Department of Water and Power initiated a project in 2019 to replace some of them with stronger metal structures.

The project stalled after environmental regulators said the department had damaged 183 small bushes known as Braunton’s milkvetch, an endangered species.

In 2020 the LADWP paid a fine and the work was supposed to continue but never did. Previous California wildfires have been sparked by power lines but there's no proof, yet, that this one was.

So there you have it. It could have been a previous fire that wasn't quite out. It could have been a group of young men in the hills that day or it could have been power poles to the north. It will likely take months before an official report is issued on what caused this.

Update: This is interesting.

BREAKING: ATF arson investigators have descended on the area of suspicion, along a hiking trail at The Summit of the Pacific Palisades #PalisadesFire pic.twitter.com/9y6ktpbMSr

— Chris Cristi (@abc7chriscristi) January 13, 2025