At 15:31 Sussex EOC transmitted a box assignment for a reported structure fire at the give address. Also due on the assignment were Truck & Engine/Tanker 84 (Millville), Engine/Tanker & Engine 76 (Frankford) & SCMES Medic 105. As units were marking up, a heavy column of black smoke could be seen in the area. E731 arrived 1st due to find a 20 ft travel trailer & an 8x10 outbuilding well involved & collapsing that had extended into surrounding brush, with exposures to numerous other large outbuildings & a residence. The crew from E731 pulled a 1 3/4" smooth bore line & began fire attack on the fire endangering the exposures. E732 arrived 2nd due, with its crew pulling an additional 1 3/4" smooth bore line to support the crew off E731. Truck 84 arrived assuming the 1st due special services position, while Engine/Tankers 76 & 84 established the water supply, while Rescue 73 set up for rehab & SCBA refill. Both Tankers 73 & 84 were staged. Units preformed overhaul & wet down the area before picking up & returning to service. Units operated for just over 45 min. The scene was turned over to DE FMO which determined from the owner that a cutting torch was being used on the travel trailer earlier in the day. Chief S. Furbush had Vines Creek Rd IC.