Nigerian officials are trying to reassure citizens about a spreading Islamic insurgency in the country's northeast where fleeing residents report that extremists are urging people to join their fight and take their children out of school.

The Defense Ministry acknowledged Saturday it faces "challenges in the counter-terrorism efforts" but repeated promises that "everything will be done to ... defeat the rampaging terrorists."

The statement did not admit that Boko Haram militants this past week overran Bama, the second largest city in Borno state, and now threaten the capital, Maiduguri. Witnesses said hundreds of soldiers have fled the fighting.

Borno Gov. Kashim Shettima cut short a trip abroad "so we can be together ... (to) overcome this challenge." He extended sympathy to those who have lost loved ones in "serial massacres."