At least 13 people were killed on Sunday in two separate attacks in Benue State, central Nigeria, an area rife with clashes between farmers and herders, according to a local official.

In the first night to Sunday attack, armed men suspected of being ranchers broke into the village of Tseadough, Kwande District, killing seven people, including women and children and taking away a pregnant woman.

The victims were killed with knives or bullets, while an old man who could not move easily died in his house.

In the city of Otukpo, still in the state of Benue, six people were killed in the same day Sunday, in another attack, according to several witnesses and a person in charge of the administration of the city.

This state has been shaken for decades by clashes between so-called “indigenous” farmers, mainly of Christian faith, and Fulani pastoralists, mostly Muslim.

This conflict, which has the bone of contention for water and land, has in part worsened because of a population explosion in the country.