A 150-litre leak of hydrochloric acid occurred around 1 am on a road tanker parked within the enclosed part of a chemical wholesale business. A city police patrol detected smoke and notified both the fire department and site operator. Wearing individual protective gear, an on-site fire-fighter drained the leaking cistern into containers while external first responders spread foam on the pooling acid. A crisis response unit was assembled. The cistern was completely drained by around 3 am. Three fire-fighters had to be hospitalised. According to inspectors, a defect in the cistern’s interior lining caused this accident. The operator implemented several preventive and corrective measures: more frequent cistern inspections, improved video surveillance (for detecting leaks or fire), and circulation of a memorandum making it mandatory to indicate cistern contents during loading steps (performed in the evening of the previous day) and no longer in the morning upon driver arrival. A cistern identification problem was actually spotted: the UN material code of bleach had been affixed instead of the hydrochloric acid code. A series of oversights also appeared when activating the internal emergency plan: inappropriate resources used (foam) by first responders to combat the spreading of acid, phone directories not updated, and defective means of communication. An emergency drill was to be conducted jointly with fire-fighting crews at least once a year for them to improve familiarity with the site, as well as with the types and hazards of products being stored.