At least 15 children have been hospitalized and nearly 30 children and adults as part of a Salmonella outbreak at several preschools in the San Fernando Valley and East Los Angeles.

The outbreak was traced to a North Hollywood kitchen that supplies food to the 29 preschools operated by the Volunteers of America of Greater Los Angeles, a faith-based nonprofit organization, said David Dassey of the L.A. Co. Public Health Department.

County public health officials inspected the kitchen, which voluntarily closed at the end of last week and reopened Tuesday. Letters were sent home to parents informing them of the situation and urging frequent hand-washing and other healthy practices.

All 29 facilities report at least one person coming down with salmonella-type symptoms, including fever, vomiting and diarrhea.