WINFIELD, Ill. (AP) — State health officials are investigating whether three cases of Legionnaires’ disease are linked to a suburban Chicago hospital.

The Illinois Department of Public Health said Friday the three people were all patients at Northwestern Medicine Central DuPage Hospital in Winfield, about 30 miles west of Chicago. One person was an inpatient, while the other two had outpatient visits.

IDPH said the three patients also had other possible sources of exposure in the 10 days before their symptoms began, so the hospital may not be the source. Most healthy people don’t get Legionnaires’ disease after being exposed.