A Spanish nurse has been diagnosed with Ebola at the Madrid hospital where two patients have been treated for the viral illness, in what is the first case of a person becoming infected outside of Africa.

The government is taking action to keep doctors and staff safe at Hospital Carlos III, and is investigating how the woman became infected, Health Minister Ana Mato said at a news conference in Madrid. The hospital was designated by the government to treat Ebola cases, and the nurse treated Manuel Garcia, a priest who died of Ebola last month.

"All measures have been taken to give the best care to the patient, and guarantee the safety of all citizens," Mato said. "We are working to know what the source of the infection was."