1951 Pont-Saint-Esprit mass poisoning
The 1951 Pont-Saint-Esprit mass poisoning, known in French as Le Pain Maudit, took place on 15 August 1951, in the small town of Pont-Saint-Esprit in Southern France. More than 250 people were involved, including 50 people interned in asylums, and there were seven deaths.
Source: Wikipedia — 1951 Pont-Saint-Esprit mass poisoning (CC BY-SA 4.0)