No one knows how many children are dying of starvation in refugee camps and areas too dangerous to access because of the extremists' presence, according to Doctors Without Borders, which runs the emergency feeding center. The aid group first sounded the alarm of a humanitarian crisis of "catastrophic" proportions in northeast Nigeria as Boko Haram lost its grip on some areas and its victims began to emerge.

A doctor feeds a malnourished child at a feeding centre run by Doctors Without Borders in Maiduguri, Nigeria, Aug. 29, 2016.
Sunday Alamba/AP Photo