January : The U.N. 's Ban Ki - moon is ` ` appalled at the frequency and intensity '' of recent violence . Nigeria closed its borders Saturday with Cameroon and Niger , whom it has accused of allowing the militants to move freely into Nigeria . A military official tells CNN that at least 156 people were killed . Nigeria closes its borders with Niger and Cameroon and imposes a state of emergency . The Islamist militant group Abu Dhabi claims responsibility .
January : The U.N. 's Ban Ki - moon is ` ` appalled at the frequency and intensity '' of recent violence . A military official tells CNN that at least 156 people were killed . Nigeria closes its borders with Niger and Cameroon and imposes a state of emergency . The Islamist militant group Abu Dhabi claims responsibility .