At 5 am, security personnel monitoring the Corbas industrial zone noticed smoke escaping from a plant manufacturing animal feed, where production had been shut down 1 hour prior. Upon their arrival, fire-fighters observed thick black smoke emanating from the machine room housing 3 refrigeration installation compressors utilising chlorodifluoromethane (R22). The Police Force, gas and electricity departments and emergency medical services were also deployed to the scene. Two distinct explosions erupted afterwards; the first was definitely of either the “backdraft” type due to an accumulation of unburned / not fully burned gases at the roof level (CO, etc.) or “flashover” type generated by a hot zone under the ceiling, injuring 2 fire-fighters present in the room. The ensuing judicial investigation could not identify the origin of the blaze. Property damage was assessed at €1.3 million and operating losses at €300,000 over a 6-month period. The operator plan to restore the 170 sq.m of roof blasted off by the explosion and rebuild the compressor room. Fire-fighters feared that a train serving the industrial zone might collide with an obstacle projected by the explosion or a burst gas pipeline running along the building connecting the external storage tank with the boiler. The Environmental Inspection Service recorded the facts and proposed an emergency order to secure the site, plus an additional order prescribing an update to the safety analysis conducted in 1997.