A second Ebola clinic run by Doctors Without Borders in the Democratic Republic of Congo was attacked in less than a week, the humanitarian group said Wednesday. The Congo, which is in the grip of the civil war, is currently experiencing a major epidemic with more than 800 people infected with hemorrhagic fever, 500 of whom have died. But residents of the region are wary of external medical workers trying to curb the spread of the virus and save lives. On Sunday night, unidentified assailants shelled a clinic in Katwa and burned it. Doctors Without Borders, known as Médecins Sans Frontières abroad, called Wednesday's attack on a treatment center in Butembo "deplorable", but provided only that few details. "This attack has not only endangered the lives of Ebola patients and their families, but also that of MSF staff and the Ministry of Health," the statement said. "Our efforts are currently focused on the immediate safety of staff and patients." The motive of the attacks is not clear, but group leaders said it was clear that the medical workers "have failed to gain the trust of an important part of population . "