ABUJA, Nigeria (AP) — At least 16 soldiers, including four officers, were killed in southern Nigeria while responding to a distress call during fighting between two communities, defense officials said Saturday.

The attack in the oil-rich, riverine Delta state happened in the Bomadi council area Thursday when the soldiers, deployed to keep the peace, “were surrounded by some community youths and killed,” Defense Headquarters spokesman Brig. Gen. Tukur Gusau said in a statement.

The attack led to the death of the commanding officer, two majors, one captain and 12 soldiers, Gusau said, adding that a few arrests had been made related to the attack, which is now being investigated by the military.

Local media reported the conflict in Delta was related to a lingering land dispute between the Okuama and Okoloba communities, which resulted in the abduction of one man. The soldiers had unsuccessfully tried to negotiate his freedom.

Though mostly deployed on special security operations across the West African country, Nigerian soldiers are sometimes sent to resolve conflict in communities, especially areas with an inadequate security presence or where deadly clashes are common.