The fire started around 3 p.m. in the 14700 block of West Aetna Street, not far from the Orange Line busway.
Fire crews rushed to control the blaze, which caused part of the roof to collapse at the height of the fire. Nearby structures were threatened by the fire and the surrounding area was evacuated as a precaution.
The blaze was knocked down shortly before 4 p.m. About 140 Los Angeles firefighters battled the blaze and confined it to a heavily damaged part of the building, where authorities said the fire started.
No one was injured.
The cause of the fire was unknown.