Massive six-alarm blaze engulfs California warehouse, employee detained

A massive six-alarm blaze tore through a California warehouse early Tuesday and authorities said an employee is in custody, FOX 11 reported.

Video from the scene showed flames ripping through the roof of the Kimberly-Clark consumer goods facility in southern Ontario, Calif., as smoke billowed into the dark sky.

Crews responded around 12:30 a.m. to the roughly 1.2 million-square-foot facility where flames were already tearing through the roof when first responders arrived, according to KTLA.

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San Bernardino County Fire said the Ontario Fire Department was battling a six-alarm warehouse fire involving paper products, with assistance from multiple neighboring agencies. Police also used drone footage to assist operations.

The warehouse contained paper products such as tissues and other consumer goods, helping the fire spread rapidly, FOX 11 reported.

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By about 5 a.m., firefighters shifted to a defensive strategy, positioning ladder trucks around the building and dousing the structure from above as the hours-long fire continued to burn, KTLA reported.

About 20 employees were inside the warehouse when the fire broke out, but all escaped without injury, according to FOX 11.

Ontario Fire Department Deputy Chief Mike Wedell said that while the building’s internal sprinkler system was operational, the fire grew "exponentially very quickly," forcing initial interior crews to retreat and adopt a defensive strategy, FOX 11 reported.

Fire officials said the incident is being investigated as an arson case and that one suspect is in custody, the outlet reported.

"At this point, we do have a subject of interest," Ontario Fire Department Deputy Chief Mike Woodell told KTLA. "That individual has been brought into custody, arrested, and taken to the police department. The individual is awaiting questioning by Ontario Police Department detectives who are en route."

Fox News Digital reached out to Ontario's police and fire departments for comment.