'Backdraft' See The Dangers Here
A backdraft is an explosive event at a fire resulting from rapid re-introduction of oxygen to combustion in an oxygen-starved environment, for example, the breaking of a window or opening of a door to an enclosed space. Backdrafts present a serious threat to firefighters, even those with a high level of experience.
Signs of a backdraft occuring include 'cauliflower' shaped smoke - the symptons will always be the same but a lot of factors go into creating a backdraft and that's why they are so dangerous.
A backdraft can occur minutes after the door has been opened or it may not happen at all beacuse it's so irregular fire fighters can get caught out.
The other effect which can be as deadly is the horse shoe named because it occurs when two doors are opened allowing the smoke two access points.