The three-alarm blaze was reported shortly after 10 a.m. in the 700 block of South 9th Avenue.
The intense fire spread quickly, and the entire roof collapsed within minutes. It quickly gutted the building, and fire crews had to battle huge walls of flames.
"It's amazing. I can't believe how long it's taken them to put the flames out, and they just continue to keep coming back," said Industry resident Rosa Giron.
Officials say the last tenant kept insulation products inside and that was a concern.
"We determined that this was a vacant building upon our initial attack," said Los Angeles County Fire Department spokesperson Scott Miller. "We did a primary search and we didn't find anybody in this building, and that's why we took that precaution of going defensive on this fire. We didn't want to jeopardize any of our personnel's lives for a vacant building."
Two firefighters were transported to local hospitals for heat exhaustion. Officials say they're going to be OK.
According to local residents, the building also was a former fruit packing warehouse. People say it was part of the area's history and that is now gone.
"I can't believe it. It just makes me want to cry," said Industry resident Ruth Beardsley.
The good news is firefighters were able to contain the fire, and it didn't threaten nearby structures. There were no people inside the building, but firefighters did rescue a brave pup that was inside. After the dog was saved, firefighters tweeted: "No life is too small to save!"
The cause of the fire was under investigation.