In Nigeria, four people were killed when a United Nations World Food Programme, WFP aid convoy was ambushed in the northeast. A WFP spokeswoman yesterday said this is the latest attack in the region as the conflict with Boko Haram nears its ninth year. <br/><br/>Attacks on aid workers are relatively rare in the conflict with the Islamist insurgency, compared with assaults on the military and civilians in Nigeria's northeast.<br/><br/>The years of fighting have spawned what the United Nations calls one of the worst humanitarian crises in the world, with 8.5 million people in need of life-saving assistance.