No smoke without fire

I was on my daily walk in my basic route, when I noticed big amount dark smoke rising up in the Linnasaari island, where I know be abandoned cottages. I called 112 immediately at 1:26 pm and fire department with their boat arrived 1:48 pm and started to kill the fire. Before their arrival flames were really high (check the extra image). Few minutes later also local lake rescue team arrived to support fire department. Afterward I got information that one of abandoned cottages was burn down and also some amount of forest around it. So far I don't know the cause for the accident, but I assume its caused by careless people(s).

There are also few more extra images.

EDIT: It was one of those abandoned cottages that was burned. Also about 300 square meters of forest burned around the cottage.