4-06 Box, 16:12 - Ridge VFD responded to 49430 Airedele Road in Ridge for reported smoke coming from a heater unit in one of the schools cottages. Ambulance 496C arrived on the scene at 16:16 and reported smoke coming from side Delta of the structure. Chief 4 arrived at 16:18 and reported a 40x60 trailer on side Delta of Ridge Elementary School with smoke showing and established the command. Engine 41 arrived at 16:21 entered side Alpha with an 1 3/4" line and began an interior attack. Squad 4 arrived on side Delta and assisted Engine 41's crew with extinguishment as well as assisting Tanker 4 with establishing a water supply. Engine 141 arrived on side Alpha and assisted crews with ventilation and overhaul. Other units responding staged on Rt.5. The fire was put under control by command at 16:28. After assisting with investigation, units cleared at 18:18. The fire is under investigation by the Maryland State Fire Marshal's Office.