Firefighters dispatched at 2:31 a.m. to 1456 S. Long Beach Ave. reported a fire through the roof of the one-story structure with its flames threatening an adjacent pallet yard, according to Brian Humphrey of the Los Angeles Fire Department. The fire was knocked down just before 4 a.m.
A firefighter suffered a non-life-threatening burn injury battling the blaze and was taken to a hospital in fair condition, Humphrey said.
The one-story building was the site of a previous burn.
The time and cause of the man's death will be determined by the coroner. The victim's name will be withheld pending notification of next of kin.
The blaze was categorized as a major emergency structure fire at 3:13 a.m., with 106 firefighters at the location and flames extending to some contents at the pallet yard and briefly threatening two nearby commercial structures.
The address of the fire was initially reported as being at 1552 E. Newton St.
The cause of the fire was under investigation.