Gunmen have killed six people, injured five and kidnapped others in Nigeria's northern Kaduna state, authorities say.

Police have not said how many people were taken but say they are working to rescue the abducted and are investigating the incident.

They say the attackers targeted several vehicles along the main road between Kaduna and Zaria, shooting indiscriminately before abducting people.

A traditional ruler’s convoy was among those caught up in the attack. The emir of Potiskum in north-eastern Yobe state was injured and taken to hospital, and local reports suggest that four of his entourage were killed.

This is the latest in a string of attacks in Kaduna and this particular road is a notorious hotspot for criminals seeking travellers to kidnap for ransom.