At 18:45 on Wednesday, May 19, the Rural Grove fire department was dispatched for a dairy barn fire on Carlisle Road. First chief that acknowledged the call requested a large mutual aid response, including from Montgomery County-Charleston, Ames, Canajoharie, Burtonsville and just across the border in Schoharie County--Carlisle. Carlisle being the closest to the scene responded their first out engine 2021 and tanker 2031 and arrived just as Rural Grove was setting up attack. Ames was requested immediately to set up a tanker filling operation and they performed marvelously. Double dump tanks with siphons between dump tanks were used for both primary scene pumpers--1 from Rural Grove and 1 from Charleston. As is normally the case, the dairy barn was a total loss and only a free stall addition was saved. Several exposures were saved--a small shed and the farmhouse. Apparently there were service personell looking at problems in the milkhouse on the vacuum pump and they left for a more urgent call, and when they returned the barn was starting on fire. The investigators were focusing on that area when I left the scene and am unsure of a final cause. Eventually Esperance from Schoharie County was also brought to the scene with 2 pumper tankers to support the large volume of water, and Sharon Springs set up a a pond in Carlisle to provide water source #2. There were many departments put on standby but I don't have any details. Mutual aid released around 21:00. As firefighting was starting overhaul, the owner of the complex felt the need to get on his bulldozer and start demolition, but he was quickly stopped until investigation could proceed. No loss of cattle and 1 firefighter complained of difficulty breathing and chest pain and was transported by ambulance.