Fire investigators are trying to determine what caused a house fire in Brimfield that killed a man. Authorities say the house was fully involved when firefighters arrived on the scene early yesterday morning. The victim's name was not immediately released. Authorities say he was the only person in the home at the time of the fire. Meantime, in Belchertown officials are continuing to investigate Wednesday's fire at a mobil home park. Officials say Walter Lysak Sr made it out with the clothes on his back, but lost two cats that were inside. No cause yet.