June 20 (UPI) — Los Angeles Mayor Karen Bass on Saturday issued a declaration of local emergency as the city continues to fight a major fire at a cold-storage warehouse in the city’s Boyle Heights neighborhood.

The fire erupted on June 17 and has since caused smoke to blanket the surrounding area as the warehouse continues to smolder, leading the city to open 24-hour-per-day smoke relief centers for resident who cannot shelter-in-place.

The fire, which was described by Los Angeles Fire Department Chief Jamie Moore as “a very unique challenge,” started around 2:30 p.m. on Wednesday at the 500,000-square-foot building, ABC7 and The Los Angeles Times reported.

Fire officials said that hazardous materials, including ammonia, have been removed from the building, but foam insulation inside of the building’s walls, among other things, continues to burn.

“While the LAFD continues making progress, this is a major, multi-jurisdictional incident,” Bass said in a statement announcing the declaration.

“The City and County have opened spaces for families seeking relief from the smoke, and we will continue working around the clock and doing everything possible to put this fire out completely,” Bass said.

The ammonia at the warehouse has been pumped out and transported elsewhere, Lineage Logistics, which operates the facility, said in a statement.

The company also said that it believes the fire started when a neighboring business tested a solar array on Wednesday.

Aside from the insulation, city officials said that they also concerned about the rooftop solar array and lithium-ion batteries at the warehouse catching fire, as well as eventually clearing out roughly 85 million pounds of decaying — if not also burnt — food products, most of which is meat.

The LAFD has worked since Wednesday to ventilate the building so that firefighters can more safely enter the building to suppress the fire, department spokesperson Lyndsey Lantz said in a series of updates posted on its website this week.

which carried with it warnings for residents in the surrounding area to avoid smoke inhalation.

Although much of the smoke from ventilating the building had started to clear by mid-day on Friday, an anticipated change in the wind on Friday after, which caused the fire to also flare up, made smoke more visible than it had been since Thursday.

“LAFD crews continue to work diligently on the warehouse fire in Boyle Heights,” Lantz said in an update at 10:00 a.m. on Saturday.

“The smell of smoke has reached most of the city, and we encourage everyone to limit exposure as much as possible.”