The fire at Jefferson Street and Pueblo Avenue was reported shortly before 1 a.m. today.
A second alarm was called shortly after that, and firefighters had the fire under control about an hour later, Battalion Chief Steve Stuart said.
The 250-foot by 50-foot single-story commercial structure houses seven businesses and all were heavily damaged by the fire, Stuart said.
One firefighter suffered minor injuries. There were no other injuries to firefighters or civilians, Stuart said.
Firefighters remained on the scene for several hours after the fire was contained.
The cause of the fire is under investigation.