Introduction – In late March 2024, three cases of salmonellosis were reported at a preschool in a municipality in the Pays de la Loire region. In the weeks that followed, additional cases were reported, affecting three schools (preschools and elementary schools). Methods – A multi-agency investigation was conducted, encompassing epidemiological, veterinary, and microbiological components, to identify the source of the contamination. Results – The investigation identified 41 symptomatic cases of salmonellosis among students, including 19 cases with microbiological and genomic confirmation, 15 probable cases (microbiological confirmation), and 7 possible cases (without microbiological confirmation). In total, 49% of cases were under 5 years of age. The attack rate among the 803 students was 5.1%, whereas it was 19.1% among children in the youngest kindergarten class. The epidemic strain is a monophasic variant of Salmonella enterica serotype Typhimurium ST34; HC5_111251; HC2_122719. A single common location was identified among these three schools: the school cafeteria. The veterinary investigation led to suspicion of raw cow’s milk cheeses present in the school cafeteria and at the producer’s facility. The outbreak strain was isolated in “raw milk tomme” cheeses, sampled from the cafeteria and the production farm. No source of contamination was identified at the farm. The remaining batches of the affected cheese were withdrawn from sale and destroyed. Conclusion – This investigation underscores the importance of adhering to the recommendation not to serve raw cow’s milk cheeses to young children in institutional settings, particularly those under five years of age. The absence of heat treatment of the milk makes it impossible to control potential contamination by pathogenic bacteria.