A fire that broke out Wednesday afternoon at a cold-storage warehouse in east Los Angeles continued to smolder Saturday and send plumes of smoke through the region.

Jaime Moore, the Los Angeles fire chief, described the blaze as a “unique challenge” because the walls of the warehouse were made of insulated material that burned slowly and emitted gas. He added that there was no visibility inside the warehouse, located in the Boyle Heights neighborhood, making it difficult for firefighters to remove its contents.

No injuries have been reported, and shelter-in-place orders were lifted on Friday. Still, officials urged residents, especially older adults and those with underlying health conditions, to be mindful of the smoke and to limit time outdoors.

Mayor Karen Bass on Saturday issued a declaration of a local emergency to help mobilize mutual aid and other resources. “This is a major, multi-jurisdictional event,” she said in a statement. “I’m issuing an emergency declaration to ensure the city has the resources it needs as this operation continues and to keep the community safe.”

Here is what we know.

Why is the fire still going?

Chief Moore said fighting the fire was complex because the building was essentially a freezer made of corrugated steel and insulated with dense foam. Ammonia was used as a refrigerant, and firefighters initially had to remove all of the ammonia.

Adding to the difficulty, some fire was smoldering below structural debris and solar panels. The building is quite large, but firefighters have isolated the fire to one area, using hoses that emit up to 2,000 gallons of water per minute. Chief Moore said firefighters were now working to remove the millions of gallons of frozen food before the food became a biohazard.

What is the facility?

The warehouse is a roughly 500,000-square-foot commercial building, about the size of 10 football fields, that stores about 85 million pounds of frozen food. It is owned by Lineage Logistics, a warehouse company based in Michigan and was built in 2018.

A spokeswoman said the company believed the fire began while contractors of the owner of the solar panels on the roof of the building were conducting testing. She added that the facility is not used for storing hazardous materials.

The warehouse also ignited in August 2024, but firefighters were able to extinguish the flames in 48 minutes, according to the Fire Department.

Are there health concerns?

Dr. Muntu Davis, Los Angeles County health officer, said the smoke could cause temporary irritation of the ear, nose and throat and could exacerbate existing health and lung conditions.

He encouraged people to limit their exposure to smoke, close their windows and orient their HVAC system such that it was not pulling air in from the outside. He also encouraged people spending time outdoors to wear a mask.

The American Red Cross helped to open up two smoke respite shelters, one at the Pecan Recreation Center and another at City Terrace Park.