Ammonium nitrate
Ammonium nitrate, which is predominantly used as an agricultural fertilizer, oxidizing agent in explosive compositions, and in manufacturing of other chemicals, has been inculpated in a number of other fatal industrial explosions. A fire department spokesman confirmed that firefighters had used water in combating the initial fire, which may have led to water being sprayed on calcium carbide, releasing the highly flammable gas acetylene. This would have provided the fuel source for reaction with the oxidizer, ammonium nitrate, thus triggering its detonation more readily.