IOWA CITY, Iowa (AP) — Hospital administrators have acknowledged that more than 60 employees at the University of Iowa Health Care campus in Iowa City have tested positive for COVID-19. The Gazette reports that of the 64 employees infected to date, four tested positive Thursday.

UI Hospitals and Clinics CEO Suresh Gunasekeran says the outbreak is not due to a failure in the hospital’s personal protective equipment strategy. But he conceded that administrators don’t know how or where all the employees were exposed, noting that the virus has “been so prevalent in different parts of the community that we’re just unclear.”