The fire was reported just before 12 p.m. at a two-story storage facility near Industrial and Mill streets, according to the Los Angeles Fire Department.
Fire officials said the facility was undergoing demolition when flames erupted inside and briefly trapped a demolition worker who was able to get out of the building.
The blaze, known as the Industrial Fire, escalated to a "major emergency" with 117 firefighters responding to the incident, fire officials said.
Around 1 p.m., fire officials reported the blaze was knocked down.
No injuries were reported.