KINSHASA (Reuters) – Attackers set fire to an Ebola treatment center run by Medecins Sans Frontieres (MSF) in eastern Democratic Republic of Congo late on Sunday, forcing staff to evacuate patients, the charity said.

There were no immediate details on the identity or motive of the people who torched the center in the district of Katwa, at the heart of the country’s worst outbreak of the deadly disease.

But the World Health Organization has said aid workers face mistrust in some areas, fueled by false rumors about treatments and preference for traditional medicine.

“As a result of the burning of the building, it is no longer possible to care for patients there,” MSF said on Twitter on Monday. None of the patients or staff were harmed, it added.

The outbreak has killed 546 people since July, according to the Congolese health ministry.

Most of the cases since the start of the year have been in Katwa, which is close to the border with Uganda.

Three volunteers for the Congolese Red Cross were attacked as they helped with the burial of an Ebola victim in eastern Congo in October. Two months later, political protesters ransacked a nearby Ebola isolation center.

(Reporting by Fiston Mahamba and Giulia Paravicini; Editing by Juliette Jabkhiro and Andrew Heavens)