The authorities in Ghana say 1,000 soldiers and police officers are being deployed to a north-eastern border town after gunmen killed an immigration officer and left two others in the hospital.
It is not yet clear who opened fire on their vehicle in Bawku but there is concern about the security situation there because of the escalating jihadist conflict in neighbouring Burkina Faso.
There are fears that Islamist militants causing havoc across the Sahel region could destabilise countries further south - including Ghana and Ivory Coast.