At least 10 people have been killed in north-eastern Kenya after their vehicle ran over an explosive device on a major road.

North Eastern regional police commander George Seda said the blast occurred outside Mandera town.

It is not clear how many people were in the vehicle, and witnesses said the toll could rise because others had serious injuries.

Police suspect the explosive device was placed by al-Shabab extremists operating in the area after crossing from nearby Somalia.

The extremists are often blamed for such attacks in the border region, targeting both security forces and civilians.

A police report on Monday's blast said the attackers fled toward the border.