Authorities in Kenya say at least 28 people have been killed in clashes between two rival ethnic groups in the southeastern Tana River region, where deadly violence broke out earlier this year.

A local police official says a group of ethnic Pokomo raided a village belonging to the Orma people in the pre-dawn hours of Friday.

The two groups have waged a series of deadly attacks and revenge missions as part of an ongoing dispute over land and water.

In August and September, more than 100 people were killed during clashes between the Pokomo, which is largely a farming community, and the Orma, which consists of mainly herders.