A U.S. resident who contracted the Ebola virus in Sierra Leone passed away at the Nebraska hospital where he was being treated. Dr. Martin Salia, 44, was airlifted out of Sierra Leone and arrived at the University of Nebraska Medical Center on Saturday. “It is with an extremely heavy heart that we share this news,” said Dr. Phil Smith, director of the hospital’s biocontainment unit. On Sunday, Salia’s prognosis was not optimistic. The hospital described his case as an “hour-by-hour situation” and warned that he was critically ill. Salia is the tenth known Ebola case in the U.S. and the second to end in death. His death comes as some of the countries hit hardest by Ebola, such as Liberia, appear to be quelling the epidemic. Ebola has claimed the lives of more than 5,000 people in Africa.