Officials from the World Health Organization (WHO) have budgeted more than 100 million USD to fight the Ebola Virus outbreak in the eastern portion of the Democratic Republic of Congo (DRC). However, that amount may not be enough if violence in North Kivu province — which is the epicenter of the outbreak — continues to hinder the efforts of medical workers.

According to Reuters, a local militia attacked a group of aid workers over the weekend and killed 14. The attackers also took several civilians hostage. The frequency of attacks has the Congolese military on high alert, and according to a report from Foreign Policy, the militia groups have transformed the region into a “war zone.”

“When we arrived at the airport we noticed that the area is heavily militarized,” said ALIMA (The Alliance For International Medical Action) physician Dr. Marie Claire Kolie while speaking to the Associated Press. “Personally it scared me a little, I must say. But… we can’t just leave these people.”

Dr. Kolie’s fears might be more than just paranoia. According to a report from Time, medical workers in North Kivu are being attacked “three or four times a week on average.”

Several militia groups are operating in the border region between the DRC and Uganda. The most aggressive is the Allied Democratic Forces (ADF), a Uganda-based radical Islamist group that has a history of attacking Congolese military units. Many of the healthcare workers are members of the Congolese armed forces, making them lucrative targets for ADF terrorists.

“It’s a sad day for all response teams who sometimes put their life in danger while serving the country. Health workers should not be a target for armed groups,” said Congolese Health Minister Oly Ilunga, according to Reuters.

António Guterres, the current United Nations Secretary-General, joined Ilunga in calling for an end to the violence, saying that he “is outraged by the continued killing and abduction of civilians by armed groups,” according to UN press release.

Officials from the WHO stated earlier this week that the current response to the outbreak needs to be increased if the virus is to be contained, and that the rate in which Ebola is spreading has quickened over the last two weeks.