Fire Rapid sustained oxidation with the emission of heat and light. If oxygen is limiting combustion may be incomplete. For example instead of carbon dioxide being produced carbon monoxide may be released. Acetylene may combine with itself to produce a polymer - long chain carbon molecule. Already in the vapor state so less energy is needed to start and sustain the combustion process.
Air temperature rises rapidly, heated gases and radiant energy spread fire.
At about 1300 o F all combustibles ignited. The entire contents of the compartment reach the ignition temperature almost simultaneously and ignite. Heat still high and chain reaction is only limited because of low oxygen. A smoke explosion - caused by the addition of oxygen to a smoldering phase fire. The oxygen completes the fire triangle and lets the chain reaction go.