The massive Saddle Ridge fire started under a high-voltage transmission tower, Los Angeles fire officials say

Investigators now know where the mammoth Saddle Ridge fire started. They just don’t know how.

The blaze, which has torched more than 8,300 acres, started in a 50 feet by 70 feet area under a high-voltage transmission tower, the Los Angeles Fire Department said.

But the cause of the fire remains undetermined, LAFD said Tuesday.

The inferno is still raging, with only 52% containment as of Wednesday night.

“Investigators continue to work around the clock in steep terrain, thoroughly examining all aspects of the scene in an attempt to determine a cause,” LAFD spokesman Nicholas Prange said.

About 100,000 people were forced to evacuate, but all evacuation orders have been lifted.

The wildfire has destroyed at least 17 structures and damaged 77 others, LAFD said.

Three firefighters suffered minor injuries battling the blaze, and one civilian died after suffering cardiac arrest, the fire department said.

Electricity company Southern California Edison’s system was “impacted” near the time and place where the fire first broke out, utility spokeswoman Susan Cox said.

The fire started around 9 p.m. Thursday near Yarnell Street and Saddle Ridge Road in Sylmar, “which quickly spread westward in the northern part of Los Angeles,” said Sally Jeun, another SCE spokeswoman.

Jeun would not confirm whether the high-voltage transmission tower near the fire’s origin is owned by SCE.

SCE notified the California Public Utilities Commission about an “electrical incident” Friday night. But details of the report are considered confidential and are not publicly available at this time, California Public Utilities spokesperson Terrie Prosper said.

She said utilities are required to report any incident that involves a fatality, damage in excess of $50,000, significant media interest or a major outage to at least 10% of the service area at any one time.