A fire that damaged a Muskoka Lakes cottage at 1041 Hesners Road is under investigation. It happened last night. At 9:21pm firefighters found a 420 pound propane tank self-venting through its relief valve onto the structure. After controlling the propane tank, the fire was contained to the upper floor/attic and a washroom on the main floor. At the time of the call, there was a violent thunder and lightening storm in the area which is believed to be a contributing factor. No one was home at the time of the incident and no one was injured. The Fire Marshal’s office has been contacted and the investigation continues.