Gunmen have kidnapped more than 50 children from three schools in the same town in north-eastern Nigeria, teachers and residents have said. Most of those missing are aged between two and five years old. Eyewitnesses who saw the attacks on Friday morning in Mussa, Borno state, say the suspects used the children as human shields while fleeing on motorbikes, preventing security forces from opening fire. No group has claimed responsibility for the attack, and government officials have yet to