The St. Paul Fire Department was called to the apartment on the 2200 block of Hillcrest Avenue around 3:00 a.m.
When crews arrived, they found smoke in a first-floor apartment and evidence of a fire in a closet.
The fire department said the fire was already extinguished by a sprinkler system before they arrived.
As a precaution, the fire department searched the building to make sure all occupants had been able to evacuate safely and ventilated it.
The cause of the fire is under investigation, but the fire department said a working sprinkler system and smoke detectors prevented a much larger incident.
