"Following the most recent Butembo attack, WHO and partners are working to ensure the safety of the patients and staff," the release said. "Patients have been transferred to the Katwa transit center, which WHO is expanding to house and treat these additional patients."
Doctors Without Borders and WHO reported that all staff had been accounted for following the February 24 attack in Katwa and a 27 February attack in Butembo.
As of 26 February, the region has suffered 879 Ebola cases, of which 499 or 57 percent were female and 264 or 30 percent were children aged less than 18 years, according to the WHO.
The largest Ebola outbreak to date killed more than 11,000 people in the West African nations of Guinea, Liberia and Sierra Leone between December 2013 and April 2016.