Humanitarian aid workers are often the target of armed groups in conflict areas. Recently in Nigeria, Boko Haram militants killed two aid workers they had kidnapped. In the Democratic Republic of Congo, civilians threw stones at health workers fighting the spread of Ebola Virus Disease. One day earlier, rebels shot and killed two Congolese army medical workers. A research group called Humanitarian Outcomes has examined records documenting the problem. It says 139 aid workers were killed worldwide in 2017. Another 102 were wounded, while 72 others were kidnapped. The group says most attacks against aid workers took place in South Sudan, Syria, Afghanistan and the Central African Republic. Already this year, over 80 aid workers have been killed. The findings were published in the report of a project of Humanitarian Outcomes, called the Aid Worker Security Database. The London-based group says the kidnapping of aid workers by armed groups is becoming increasingly common.