The Christiana Fire Company was alerted to the fire shortly after 4:30 pm in the 900 block of Rue Madora Drive.
Crews arrived on the scene to flames coming from the two story townhome.
The fire quickly went to a second alarm and several neighboring fire companies responded to assist.
Investigators were called to the scene and have determined that the fire originated in the rear of the residence and was caused by discarded smoking materials
Two townhouse units were completely destroyed and three others were heavily damaged.
Fire damage is estimated at several hundred thousand dollars.
One resident suffered a minor injury and was taken to Christian Hospital for treatment.
Several families have been displaced by the fire and are being assisted by the Red Cross of Delmarva.
No firefighter injuries were reported.