As the Los Angeles area braces for another wind system to move in this week, and emergency responders there continue to battle wildfires that erupted last week, investigations are underway to try and determine what might have caused some of the most destructive fires in California’s history.

The Bureau of Alcohol, Tobacco, Firearms and Explosives has now taken the investigative lead in the Palisades Fire, where over 23,000 acres have now burned, and aerial imagery shows approximately 5,000 structures damaged or destroyed as of Monday.

Investigators are looking into possible causes — including arson or the potential rekindling of a fire in that same area that had been started by fireworks on New Year’s Eve, according to fire officials.

One possible theory that has neither been substantiated nor ruled out as of Monday, according to officials, is the involvement of transmission lines or electric facilities in inciting any of the LA County fires.

In Altadena, where over 14,000 acres have burned and over 7,000 structures are thought to have been destroyed or damaged by what is known as the Eaton Fire, investigators are examining Eaton Canyon in their hunt for clues.

Witnesses shared with ABC News Ring cam and cellphone videos that appear to show what they believe to be the start of the Eaton Fire at the base of a transmission tower in the canyon.

Fire officials told ABC News they are aware of the videos and that they are part of the investigation.

But Edison International, the parent company of one of the country’s largest electric utilities, Southern California Edison, which owns transmission lines in that area, said it has not seen evidence that electrical equipment there started the blaze.

In a report filed with the state, Edison said “no fire agency has suggested that SCE’s electric facilities were involved in the ignition or requested the removal and retention of any SCE equipment.”

It also said that there were no signatures in the energy reports from the evening of ignition, which was Jan. 7, that would indicate a causal relationship between the energy lines and the fire.

The report stated that “preliminary analysis by SCE of electrical circuit information for the energized transmission lines going through the area for 12 hours prior to the reported start time of the fire shows no interruptions or electrical or operational anomalies until more than one hour after the reported start time of the fire.”

“Typically, when there’s a spark created by equipment, you will see that kind of electrical anomaly. We haven’t seen that,” Pedro Pizarro, president and CEO of Edison International, told George Stephanopoulos on “Good Morning America” on Monday.

“That said, we have not been able to get up close to the equipment yet because firefighters have not deemed the area safe for entry,” he continued. “As soon as we can get close to it, we’ll inspect and we’ll be transparent with the public.”

Edison has said it has received evidence preservation notices from attorneys representing insurance companies with regards to the Eaton Fire.

In Sylmar, the Hurst Fire burned nearly 800 acres before firefighters achieved 97% containment on Monday.

Edison said fire agencies are investigating its equipment there, but Pizarro said the company doesn’t know whether its downed equipment in the area has any connection to the fire’s start.

“We did say that we saw damage to the equipment, but we did notice that the reported start time of that fire was 10:10 p.m.,” Pizarro told Stephanopoulos. “We first saw an electrical anomaly in our system at 10:11 p.m. And so with that being so close in time, we don’t know whether the damage happened before or after the start of the fire.”

Officials have not determined causes of any of the fires yet.

Pizarro told ABC News that SCE, one of the county’s largest electric utilities, has notified about 450,000 customers that their power might need to be shut off as another wind system picks up this week, as part of the company’s Public Safety Power Shutoffs and Wildfire Mitigation Plan.

Pizarro noted that planned power shutoffs come with risks and consequences for customers — but added that officials have said the power shutoffs SCE did ahead of the Eaton Fire saved lives.

Most major privately-owned utility companies in California utilize Public Safety Power Shutoffs in some fashion, but the companies have the ultimate say as to when and where they decide to preemptively shut off power to customers as a last resort in trying to prevent a wildfire in particular weather conditions.

In a statement released Jan. 8, SCE said its distribution lines “immediately to the west of Eaton Canyon were de-energized well before the reported start time of the fire.” It also said the company was conducting a review of the event.

LADWP, a municipally-owned utility company that services the Pacific Palisades, told ABC News that it does not use Public Safety Power Shutoffs in the City of LA. Instead, the company says it uses technology known as automated automatic circuit reclosers “to prevent circuits impacted by wind from re-energizing during high winds if they experience an outage or disruption.”

Fire investigator and engineering experts told ABC News that this type of technology can be too little, too late.

“The big difference between what they [the LADWP] do and Public Safety Power Shutoff is: PSPS is preventive. You do it because you don’t want anything to happen and you anticipate the high fire risk and de-energize,” said Ali Mehrizi-Sani, an electrical engineering professor at Virginia Tech.

“Blocking reclosers is actually reactive. Something happened and just to make sure you don’t make it worse, you de-energize the line,” Mehrizi-Sani added.

Officials have not suggested that LADWP electrical equipment had anything to do with the Palisades Fire.

“We also have very little Tier 2 high fire prone areas in the City of LA,” LADWP told ABC News, referring to the classification system tier that delineates elevated risk of wildfires.

“We worked closely with LAFD to develop this program to protect public safety while also maintaining service in our highly urban area with many hospitals and other power-dependent facilities,” the utility company said.