Fort Worth firefighters operated at a single-alarm commercial building in the 400 block of E Rosedale early Thursday morning.
Although homeless people were believed to have been in the building at the time, there were no injuries.
The cause is under investigation.
Crews began an interior attack on the smoky fire and were pulled out when conditions got bad.
Four engines, two trucks, squad, two battalion chiefs responded.
The fire was under control in 75 minutes.