The bombing targeted the No. 12 express train, which derailed while traveling at high speed near the small village of Blacy, Marne between Vitry-le-François and Loisy-sur-Marne. On the day after the derailment, investigators found that the rails had been sabotaged using an explosive device that went off when the train passed over it. It also emerged that the stationmaster at Vitry-le-François had earlier received a threatening letter from the OAS.[3]
The sabotage theory was ruled out despite a threat letter being received a few days earlier, prompting Communist Party leader Jacques Duclos to demand an inquiry on the matter.[4] Despite this, the attack was kept secret by the French state.[5]
^"Journal officiel de la république française"(PDF). 30 January 1962. p. 3. Archived from the original(PDF) on 24 September 2015. () "2294. — 2ß décembre 1951. — M. Jacques Duclos expose à M. le ministre des travaux publics et des transports : a) que le 18 juin 1961, vers 15 heures 10, le train rapide n° 12 Strasbourg—Paris déraillait à la hauteur du petit village de Blacy (Marne), entre les gares de Vitry-le-François et Loisy-sur-Marne[...]e) que le chef de gare de Vitry-le-François avait reçu avant le déraillement une lettre de menaces de l'O. A. S. disant[...]"