Major warehouse fire in Los Angeles forces shelter-in-place order; ammonia and potential battery hazards complicate response

A large fire broke out Wednesday afternoon at a 500,000 square-foot cold storage and freezing warehouse owned by Lineage in the Boyle Heights neighborhood of Los Angeles, prompting city officials to order nearby residents to shelter in place due to the release of toxic ammonia and thick smoke.

Approximately 110 firefighters from the Los Angeles Fire Department, along with additional personnel and hazmat teams from the city and Los Angeles County, responded to the blaze. The fire initially engulfed the solar panel-covered roof of the facility. Firefighters attempting to extinguish the fire using hand lines on the roof were forced to retreat after an ammonia refrigeration line burst, releasing a large volume of pressurized ammonia gas. LAFD Chief Jaime Moore explained to NBC News 4: "At some point, an ammonia line was compromised and we had a large, pressurized off-gassing of ammonia." Cold storage facilities commonly use ammonia as a cost-effective refrigerant, despite its toxic and flammable properties.

Due to the intensity and hazardous nature of the fire, firefighters took the unusual step of deploying at least three helicopters to douse the blaze from above, delivering more than half a dozen water drops while personnel retreated from the roof. Los Angeles Mayor Karen Bass urged residents in the affected area to remain indoors, close windows and doors, turn off air conditioning, and avoid unnecessary travel to minimize exposure to the contaminated air.

By evening, the roof fire had been largely contained, but the building's roof showed signs of sagging. The presence of solar panels raised concerns about potential lithium ion battery storage systems used to store solar energy. Chief Moore identified lithium ion batteries as "one of our newest challenges in the fire service," noting that they can undergo thermal runaway, a process that makes fires extremely difficult to extinguish and produces hazardous smoke. The cause of the initial fire remains under investigation.