Warehouse roof fire triggers smoke alert in Los Angeles

A massive warehouse fire in downtown Los Angeles spread rapidly, prompting a shelter-in-place order and forcing firefighters to retreat due to an ammonia gas release.

Flames swept the roof ​of a massive warehouse in downtown ​Los Angeles on Wednesday, quickly spreading ‌across ​the building's solar panels, belching thick clouds of smoke and ammonia gas that prompted a shelter-in-place order for nearby ‌residents. The blaze erupted around 2:30 p.m. (2130 GMT) at a 500,000-square-foot (46,450-square-meter) Lineage company warehouse in the city's historic Boyle Heights neighborhood, with flames breaching a pressurized ammonia line but ‌mainly burning across the roof, according to Los Angeles Fire Department Chief Jaime Moore.

The ‌burning building and adjacent structures were safely evacuated, and no injuries were reported, Moore said. Firefighters who initially scaled the building and rushed into the facility were ordered to retreat after the ⁠ammonia release, and ​crews experienced difficulty ⁠reaching the burning roof with streams of water unleashed from the ground, Moore told reporters.

In an unusual ⁠move, fire commanders ultimately called in water-dropping helicopters that swooped in and brought the ​fire under control with repeated aerial drops on the blaze, Moore said. The building is ⁠located adjacent to a major downtown freeway.

Local authorities issued a shelter-in-place order advising residents of nearby homes ⁠to ​stay indoors with doors and windows closed and air-conditioning shut off as a precaution against exposure to thick smoke and ammonia fumes. Moore said the smoke ⁠and ammonia gas were not considered toxic to individuals "unless they have respiratory issues or ⁠in direct contact with ⁠it." He said monitoring of air quality downwind of the fire and water runoff showed there was no dire threat ‌to surrounding ‌communities.