Flames were first spotted shortly after 3:00 a.m. on the unit block of Gull Turn.
Authorities say the fire started in one townhouse and spread to a neighboring house.
Ten adults and three children were displaced by the fire and are being assisted by The Red Cross of Delaware.
The Delaware State Fire Marshal's Office says the fire originated in the kitchen, caused by unattended cooking.
Damage is estimated at approximately $100,000.