When I was fostering a brother and sister were brought to me by social services, the girl being 2 years of age and the boy 4 years.
It was a very harsh winter, and the little girl was unwell, so Mum had to pop out for some bread - just down the road. She really was only out for 15 minutes, but during that time, the little girl had poled a piece of paper through the fireguard to the electric fire - it caught alight and she dropped it in fright onto the nylon rug in front of the hearth, which started to melt and burn.
Her brother pulled her out of the room and shut the door and so prevented both of them being seriously injured. Mum arrived back just as police arrived, and Dad also got home, having been called from work. When he was told his wife was being questioned by police, and the children taken into care, he punched a Police Officer, so was himself arrested!!!!
Children were taken into care, stayed with me about six weeks, but thank goodness were returned to parents without any action being taken.
Just a comment as to how a five year old, instinctively re-acted absolutely correctly to a fire.