At 2110 yesterday Riverhead fire dept. was dispatched to 1795 Main Rd, Jamesport for a structure fire. The first responding units found a potato barn fully involved. Riverhead FD assisted at the scene along with Mattituck FD. Riverhead Ambulance stood by in case of any injuries. And Flanders FD. Stood by at Jamesport firehouse. The scene was turned over to Riverhead fire marshal. Riverhead fire dept. was released around 2330 HRS.