Six children and one adult have been infected with pathogenic E. coli in Wake County, North Carolina, according to the North Carolina Division of Public Health.

Four of the individuals sickened have required hospitalization. Two have since been discharged and two are being treated in intensive care, likely because they had developed hemolytic uremic syndrome (HUS). Officials said the two patients in intensive care are children.

State health authorities are working with the human services department in Wake County, which includes the city of Raleigh, to determine what caused the illnesses and whether the cases are related. The patients are all from different households.

Health officials said Tuesday that they were still interviewing patients and awaiting the results of lab tests.