In an explosives production plant, a deflagration followed by fire broke out at 8:30 am inside a (16-m²) building used to assemble and store fireworks, 30 minutes after an employee entered the building looking for electric igniters. The ignition was gradual and extended roughly over 10 minutes. Fire-fighters extinguished the fire in less than 2 hours using 2 small nozzles. The building was destroyed, and a few roof tiles were projected within a 10-m radius. The accident did not result in any injuries. The day before, a “dud” (unfired fireworks) had been returned to inventory. According to the operator, the storage unit contained 78 kg of active material in the form of assembled fireworks shells. Facilities inspectors recorded these facts. An expert was called to the scene to determine the exact causes of the accident. Several hypotheses were forwarded, though none appeared to stand out (lightning, falling objects, a rodent). In light of this accident, the operator initiated an anti-rodent campaign and reassessed product stability.