The Nigerian Army massacred children in its war against Islamist insurgents in the country’s northeast, according to more than 40 soldiers and civilians who said they witnessed the military kill children or saw children’s corpses after a military operation.

Hundreds of civilians have reportedly been killed in what appears to be an ethnically motivated attack. Witnesses, speaking on condition of anonymity for fear of reprisals, reported at least 260 deaths.

The attack comes after Ethiopians recently voted in a parliamentary election. The US has previously accused Ethiopian government forces of ethnic cleansing in the Tigray region.

Witnesses describe a chaotic scene after a 13-year-old boy was killed and several others were taken to the hospital following a carbon monoxide leak at a Michigan hotel.