21 September 2001, a few dozen kilos of sodium dichloroisocyanurate (used in treating swimming pool water) was inadvertently mixed with 500 kg of ammonium nitrate in AZF's storage
- Ammonium nitrate had been spilled 20 Mixture resulted in an explosion measuring 3.4 on the Richter
- Explosion caused 7m deep x 40m wide crater
- Nitric acid and ammonia entered the River Garonne causing large-scale destruction of aquatic fauna and flora.31 people died
- 2 400 people were injured
- Many buildings, including 118 schools and 27 000 flats were damaged or destroyed
- Telecommunications and electricity networks were severely disturbed for days
- Over 1 200 households were relocated.