Nigeria's militant Islamist group Boko Haram has captured the key north-eastern town of Michika, residents say, gaining more territory in its efforts to create an Islamic state. People fled into bushes as gunfire rang out in the town, they added. Boko Haram has changed tactics in recent months by holding on to territory rather than launching hit-and-run attacks. The government called on Nigerians not to lose hope. The military was committed to defending Nigeria's territorial integrity, it said. Soldiers killed 50 militants during a raid on their hideout in the small north-eastern town of Kawuri at the weekend, the army said. Last month, Boko Haram said it had established an Islamic state in areas it controls in north-eastern Nigeria. Michika is a trading centre in Adamawa state not far from the Cameroon border.