The fire started around 9:00 a.m. Sunday at the Caviler Court Apartments, located at 6 Capano Drive.
Heavy fire was showing when crews arrived on scene and the building was evacuated. Three people were evaluated on scene and one juvenile was transported to Christiana Hospital for minor smoke inhalation.
It took fire crews about a half hour to get the fire under control.
No word on a cause at this time.