Mixtures of an oxidising substance and a fuel may react slowly at first, but the heat from the reaction will increase the rate at which the ongoing reactions occur. Therefore, even where an oxidiser and fuel mixture does not appear unstable, ongoing reactions may still lead to a fire.
The oxidising material may also intensify fire, including the potential for explosion, particularly if the fuel is stored under confinement. Therefore, at the initial stages of an incident an assessment must be made from a safe location.