Six children have been hospitalized following a suspected food poisoning outbreak at a kindergarten in the Russian city of Perm.

According to the regional branch of the Russian Investigative Committee, the children were diagnosed with acute intestinal infections. A criminal case has been opened to determine whether sanitary regulations were violated, The Caspian Post reports via Russian media.

Two of the children were diagnosed with salmonellosis. Preliminary findings suggest the source of infection was food prepared at the facility, with investigators suspecting that hygiene standards may not have been properly observed during cooking.

Officials say the children are in stable condition and receiving medical care. The kindergarten has been closed for quarantine while inspections and laboratory tests continue. Authorities are working to establish the exact cause of the outbreak and assess responsibility for the incident.