An unknown gunman shot and killed a police officer and injured a passing nurse in Heiban town in the Nuba Mountains.

The nurse, Yassir Alamin, said he had gone with the police officer to their neighbor’s house for dinner. They were returning to their homes when the gunman sprang from the bushes and started shooting at them.

The officer was killed on the spot and Alamin, who was wounded, was transferred to a nearby hospital.

He said he did not know why anyone would have wanted to attack them, though there is speculation in the town that a prisoner may have escaped from custody.

Security officials said an investigation is ongoing.