Witnesses say Boko Haram militants are rampaging through northeast Nigerian villages and selectively killing men, boys and members of the same tribe as Chadian forces that have dealt major blows to the Nigerian Islamic extremists.

Mohammed Seit of Kala-Balge village says Boko Haram fighters separated and killed people of the Shuwa-Arab community while sparing people from the Kanuri tribe to which most Boko Haram militants belong.

Seit says scores have been killed and homes in dozens of villages burned down in the past five days.

Nigeria's neighbor, Chad, has spearheaded a regional offensive and seized back major border towns from Boko Haram in recent weeks.

Separately, housekeeper Aminatu Mommodu says 68 men and boys as young as 12 were killed in an attack Tuesday on a village near Gwoza.