Nigerian terrorists killed more than 100 people in their latest attack: an extended assault on the remote northeastern town of Gamboru Ngala. Some officials have estimated the death toll at upwards of 300, after fighters spent 12 hours gunning down civilians, lobbing home-made bombs into homes and torching shops as their victims burned inside.

Nigerian officials haven't given many details of the attack. Nigerian soldiers in the town at the time reportedly fled or were killed. Surviving residents have told reporters their attackers...