One other person was severely injured after the gunmen opened fire on residents late Thursday, said Edward Egbuka, police chief in charge of the state.

Egbuka, who described the killing as an ugly trend, said it has posed a serious setback to the peace efforts in the state.

"This is a setback to the peace efforts that all stakeholders, the police, the military, and state government, have been trying to manage," he said.

The police said an investigation has been launched to apprehend the gunmen.