"There is nothing like the injustice of having to share a favorite toy or interrupt a perfect play session. Reactively, the young brain can, in a flash, ignite with emotion. We’ve all been around a child with a brain on fire; seeming to act without thinking. Unreasonable and incapable of stopping but with no discerning end game. ...The key to thwarting an outburst is to soothe the fire in the impulsive parts of the brain and get the cool headed thinking brain back in charge. Until then, the best rewards and the worst punishments are powerless against the inertia of a meltdown. The brain on fire is not a listener. And problems can’t be solved from that state.

"[Reactions] are ill-informed attempts of the survival drive of the lower brain to re-establish a sense of safety. The goal is to help the lower brain feel safe, and convince it to give control back to the front brain."  

Check out how to soothe and foster a feeling of safety, at the Gesell Institute.