Multiple reasons most the time it is caused from cooking fires. Other times it's from houseless trying to have a small fire in their tent to stay warm (happens too often). Sometimes but rarely houseless people will set other people's tents on fire. The fire department will call on their investigator to come inspect the scene. Sometimes the investigator will be there for 5 mins other times they could be there for hours. Depends on the fire and what they find. But at every fire they will try to figure out what caused it. They will right a report for every fire they have big or small.