LOS ANGELES - Mayor Karen Bass of the US city of Los Angeles on Saturday declared a local emergency in response to an ongoing warehouse fire that erupted Wednesday and generated heavy smoke, which has spread across the Los Angeles metropolitan area for several days.

"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," Bass said in a statement. "We're in contact with the governor because this has escalated to a problem where we are very concerned about the health of the community."

The emergency declaration is intended to unlock additional state resources for a complex operation that city officials described as larger than a routine structure fire. The fire broke out Wednesday afternoon at a Lineage Logistics cold-storage facility, where officials said tens of millions of pounds of frozen food are stored in a massive refrigerated building near downtown Los Angeles.

Fire officials said the building, roughly 46,000 square meters, presents unusual hazards because of its construction and contents. Los Angeles Fire Department Chief Jaime Moore described the facility as "like a giant cooler," with corrugated steel walls packed with dense foam insulation and reinforced interior panels.