Boko Haram fighters killed 68 civilians, including many children on Thursday in the village of Njaba in Nigeria’s northeastern Borno State, about 100 kilometers south of the state capital, Maiduguri.

“The attack was not immediately known because the village is very remote and our men couldn’t access the area,” a military source told Reuters.

Following the attack, militants massed in the town of Gwoza, near the border with Cameroon.