The blaze was initially reported at 12:30 a.m. at a dry cleaning business in the 3800 block of W. Slauson Avenue, according to the Los Angeles County Fire Department.
Seventy-five firefighters from multiple agencies responded to the scene and extinguished the massive flames, which at one point were shooting through the roof and high into the air.
No one was found inside the building after the hourlong firefight, nor were any firefighters injured, officials said.
"When I got here, I couldn't do nothing but break out crying," said Cheryl Corbin, owner of a hair salon that was damaged by the inferno. "I've been here 26 years and never had any problems.
"It just heartbreaking to me," she said. "Even though it's material and it can be rebuilt, it's not going to be rebuilt tomorrow. There's seven of us -- so, each one of us, this is how we make our income and take care of our families."
The cause of the incident was being investigated by the Los Angeles County sheriff's Arson Explosives Detail.