Nigeria's President has declared a state of emergency after a series of attacks by Boko Haram.<br /><br />Goodluck Jonathan vowed to crush the group as he visited the victims of a Christmas Day church bombing that left 37 people dead.<br /><br />It will mean the closure of the country's borders with Niger, Cameroon, and Chad.<br /><br />Al Jazeera's Ahmed Idris reports from Abuja.
