Thousands of Los Angeles residents were told to stay indoors on Wednesday afternoon as firefighters battled a fire that ripped through a cold-storage warehouse.

A thick plume of black smoke rising from the roof of the facility, in the city’s Boyle Heights neighborhood just east of downtown, could be seen throughout much of Los Angeles during the afternoon commute.

Residents in an adjacent neighborhood were ordered to shelter in place, close their windows and turn off their air-conditioning units because of concerns about toxic chemicals in the air. Thousands more residents nearby were advised, but not ordered, to do the same. The Los Angeles Fire Department said in an advisory around 8:45 p.m. that the shelter-in-place order had been lifted.

It was the second time in four weeks that Southern California residents had to take cover or evacuate because of an industrial incident. In late May, an overheated chemical tank threatened to wreak havoc on neighborhoods in Garden Grove, Calif., about 30 miles to south of downtown Los Angeles, before disaster was averted.

The Los Angeles Fire Department said the Boyle Heights blaze broke out just after 2:30 p.m. at the warehouse, a 491,000-square-foot facility operated by a logistics company called Lineage. Fire engines were seen surrounding the building and using hydraulic hoses to douse the building. Lineage did not immediately respond to a request for comment.

The warehouse is tucked near railroad tracks in an industrial district close to homes just off Interstate 5 and the U.S. 101 freeway, roughly five miles from downtown. Lineage, on its website, said it serves companies using the Ports of Los Angeles and Long Beach.

Firefighters initially attacked the fire by climbing onto the roof with hoses and by battling flames from the inside, said Jaime Moore, the Los Angeles fire chief. But when a pressurized gas line began releasing potentially toxic ammonia, the incident commander pulled firefighters away from the building and called for a shelter-in-place order in the area. Officials also were monitoring air quality downwind from the fire, Chief Moore said.

Near downtown Los Angeles, the shriek of emergency alerts rang out on phones as pedestrians paused and looked up to see an expansive patch of sky turn from clear blue to gray. In a statement, Mayor Karen Bass, who had been briefed on the incident, urged nearby residents to stay indoors and avoid traveling to the area.

Nearly three hours after arriving on scene, firefighters were making progress on quelling the flames by conducting water drops from helicopters. That tactic is usually reserved for brush fires, Chief Moore said, but the blaze was spreading over the flat roof much like a wildfire.

“Those water drops have proven to be effective,” Chief Moore said at a news conference.

The same warehouse ignited in August 2024, but dozens of firefighters were able to extinguish the flames in 48 minutes and prevent it from consuming the building, according to the Fire Department. The warehouse was built in 2018.

It was the third major warehouse fire in California this spring. In April, a six-alarm fire destroyed a 1.2-million-square-foot warehouse of Kimberly-Clark, the paper company, in Ontario, Calif., about 40 miles east of Los Angeles.

Last week, a fire consumed a million-square-foot warehouse storing medical supplies for Medline in Tracy, Calif., about 60 miles east of San Francisco.

Qasim Nauman contributed reporting.