A Pittsburgh hospital is investigating whether the deaths of two patients were caused by mold-related infections they may have contracted in an intensive care unit.

UPMC Presbyterian said this week that the cardiothoracic was closed Sept. 3 for an environmental cleanup after mold was discovered. Eighteen patients were relocated.

Officials say the two who died had contracted fungal infections and stayed in the unit. One was infected in October 2014, the other in June 2015.

UPMC's quality control chief says doctors don't know if the infections played a role in their deaths. A review of patient records found their infections started nearly a year ago.