Authorities said more than 100 firefighters responded to the blaze at a building in the 16200 block of Orange Avenue just before 8 a.m. There were two people inside the building when the fire erupted, but they were able to escape safely.
The two businesses inside, a packaging business and an engraving business, were completely destroyed. Fire officials say the materials inside caused the fire to spread quickly.
"The fire vented itself, and within minutes, it was completely out of control," said Inspector Quvondo Johnson of L.A. County Fire.
Crews had to fight the fire from outside after a portion of the roof caved in.
"Basically a year and a half that I had built, this company with my family, and it's all gone," said Alex Pitones of Dieworks.
The cause of the fire has not yet been determined. Pitones said his father, who was inside the building at the time, said the fire began in an office, possibly by a computer.
Orange Avenue remained closed as crews finished mopping up the area.