The blaze was first reported around 2 a.m. at a structure in a business park located along the 1500 block of E. McFadden Avenue.
The fire damaged at least three business units within the structure, which houses offices in the front and warehouses in the back.
Fire officials believe the blaze originated in a business that makes cabinets or furniture.
"The first two businesses look like either a cabinet shop, a lot of wood products, and the third business was, it looked like sewing manufacturing," said a fire battalion chief on scene.
The fire also spread to an adjacent warehouse used by a clothing company that makes flame-retardant shirts.
Santa Ana - OCFA fire investigators are onscene investigating the cause. No injuries. pic.twitter.com/BxevNDwcYL— OCFA PIO (@OCFA_PIO) September 18, 2017
Officials believe the cabinet businesses are a complete loss, but official damage estimates were not immediately available.
No one was injured in the blaze. The cause of the fire was under investigation.