At least 30 people have been killed in fresh clashes between rival farming communities in the Tana River district on the Kenyan coast, police say.
The attack by Pokomo farmers on an Orma village, Kipao, came in the early hours of the morning.
Houses were burnt and villagers cut down with machetes.
More than 100 villagers died in August and September as rivalry flared between the Pokomo and Orma communities.
Police say that there have been casualties on both sides, including women and children.
Villagers in the area have fled their homes in fear of revenge attacks.
The Red Cross say they know of at least 30 dead and 30 others seriously wounded, including a one-year-old child. More than 40 houses were set ablaze.
Search teams are said to be combing the area around Kipao, looking for further victims.
Police reinforcements and emergency officials are being flown to the scene, while the wounded are being taken to the port city of Mombasa for treatment.
In August, the two communities clashed in a dispute over Orma farmers grazing their cattle on land that the Pokomo say is theirs.
Settled Pokomo farmers and semi-nomadic Orma pastoralists have clashed intermittently for years over access to grazing, farmland and water in the coastal region.
Police, who have been camping out in the remote region, have been trying to disarm the two groups.
Tensions between the two communities have risen in recent days, they say.
The BBC's Gabriel Gatehouse says many suspect a political motive lies behind the attack.
Kenya holds a general election in March next year and an MP from the region, Assistant Livestock Minister, Dhadho Godhana, has been arrested for inciting violence. He denies the charges.
The UN says the clashes may be related to the redrawing of political boundaries ahead of next year's general election.
The last election in 2007 was marred by ethnic violence. More than 1,300 people were killed, mainly in the Rift Valley in western Kenya.