In Nigeria, at least 81 people were killed Sunday when fighters from the Boko Haram militant group opened fire on villagers in the northeastern state of Yobe. Many survivors said the massacre was retaliation for the community’s refusal to pay extortion money to Boko Haram fighters. Fifteen years of insurgency by Boko Haram has killed tens of thousands of Nigerians while displacing more than 2 million people.