what was the reason for the out of contolled fire when they tried to make the fire for the first time?

With the mention of a signal fire the boys go scampering up the mountain. Fire becomes a toy for them. They build it bigger and bigger until it consumes the top of the mountain. Golding describes it as the unleashing of an animal that the boys cannot contain. They feed it and behold a sight that is "both splendid and awful". Piggy points out the absurdness of such an inferno but, of course, nobody listens.