The Saskatoon Fire Department has determined the cause of a fire at a house on the 21 hundred block of St. George Avenue. An investigator says it was accidental, due to internal heating of discarded rags. The fire started in the kitchen. It caused $150 thousand in damages. The fire call came into the station just after four o’clock Sunday morning. The blaze burned through the roof, and some of the interior collapsed as a result.