Boko Haram militants have slit the throats of 12 people in northeast Nigeria as the army was trying to evacuate civilians from the area, a military source and a witness said on Friday.

“Just as troops were trying to evacuate some civilians from the hills so as to safeguard them from a planned air strike, some Boko Haram attacked them and slit the throats of 12 people,” a military source told Reuters.

A witness, Jonas Musa, also told Reuters his parents were among the victims.

He said soldiers had moved one wave of people from the hills around Gwoza, but before they could go back for the second, the attackers struck.

The Boko Haram problem is one of the challenges the incoming administration will face once it assumes power. 

President-elect, Muhammadu Buhari, says he is up to the task, though admitting it would be a difficult one.