At 12:06 Sussex EOC transmitted a box assignment to the Dagsboro VFD, Millsboro VFC & SCEMS Medic 103 on a reported structure fire on Possum Point Rd. Just minutes after dispatch Medic 103 marked on the air with heavy smoke visible from their quarters about 3 miles away. Engine 731 responded with a crew of five under Deputy Chief Furbush just as Medic 103 was arriving & advised they had a 14x70 mobile home heavily involved with possible entrapment. Engine 834 (Millsboro) arrived under Chief Gum correcting the address to White Oak Ct in Colonial Estates & confirming Medic 103's report. Engine 731 arrived moments behind E834 with Deputy Furbush establishing IC. E731's crew stretched a 1 3/4" smooth bore attack line to side "A". As fire attack was getting underway it was confirmed that all subjects were out of the residence & accounted for. Tankers 73 & 83 arrived establishing a water supply to both attack engines. E732 arrived & stretched a 2nd 1 3/4" smooth bore to support the hose teams from E731 & E834. Crews operated for over 2 hrs before returning. The cause is under investigation by the Delaware State Fire Marshals Office.