The operator of a chemical products depot got mixed up and had a driver deposit 3 m³ of sodium chlorite into a 30-m³ container of ferric chloride. The mixing of the 2 incompatible substances realeased white smoke followed by the explosion of the container. Pieces of the container were projected and provoked the partial destruction of 6 of the 12 adjacent tanks (domino effect). The chemical products (hydrochloric and sulphuric acids, ammonia, oxygenated water, etc.) stored in the affected tanks spilled into the retention ponds. A toxic cloud drifted in the direction of a national highway near the depot. Based in the vicinity, firefighters quickly cordoned off a safety zone, closed the road to traffic (for 2½ hours), neutralised first the FeCl3 that had escaped with soda ash and then retention basin contents with a soda lye. Gaseous emissions could be contained through the use of foam. Two mild injuries were reported, and one firefighter became intoxicated while changing protective respiratory gear. The natural environment was slightly polluted (since the stormwater drainage system shutoff was activated a bit late). An emergency order was issued to ensure subsequent site safety.