It happened just after 8 a.m. on the 2800 block of Lee Street.
Crews say they saw heavy fire and smoke coming from the third floor when they arrived, with the building housing a store on the first floor and apartments on the two floors above.
Chopper 6 was overhead as flames could be seen shooting from the roof of the building.
Firefighters were forced to battle the blaze from outside, as conditions inside became too dangerous.
There were no injuries reported.
The fire was placed under control in about an hour.
The cause of the fire remains under investigation.