Fire crews were dispatched at about 3:50 a.m. to 519 Alta Woods Blvd. after reports of a fire at the structure, officials said.
When firefighters arrived, smoke and flames were coming from the building, according to the department.
After the fire was extinguished, investigators determined the apartment had no active utilities, fire officials said.
The fire was found to have been started by human involvement, although the motive remains unknown, according to the chief.
One firefighter was hurt and taken to a hospital for observation. The firefighter is expected to make a full recovery.
No other injuries were reported.
