The raid on Kipao village in the Tana River delta in the early hours “unleashed terror” on the inhabitants, police said.
The total number of people killed was 39, including 30 villagers and nine assailants, a police officer in the region who asked not to be named told AFP. Police had earlier put the toll at 28.
Pictures posted on the Twitter feed of the Red Cross, which said earlier that 30 people had been killed, showed the charred walls of mud huts still standing, their thatched roofs reduced to nothing.
The violence could be linked to Kenya’s general election being held in March as a change in district boundaries has led to a shift in the balance of power between the different ethnic groups in the area.
The Red Cross said its rescue teams were tending to the wounded, some 30 of whom were in a critical condition. It gave no total figure for the number of people injured.
In August and September more than 100 people were killed in violence between rival communities living along the Tana River, whose muddy red waters are flanked by dense vegetation.
Police were unable to stop the violence between the Orma who are herders and the Pokomo who are mainly farmers, and some 10 officers were killed. Around 1,000 men from the special police forces had to be deployed to restore order.
It was not immediately clear whether Kipao village is peopled by Orma or by Pokomo.
Tensions have long existed between the two communities, with conflicts flaring over access to land and water points. Observers who saw the violence in August and September however said the raids were very well organised and some of them involved militia from other areas.
Tensions between the two communities resurfaced in the past few days during a disarmament operation.
“There has been tension in the last two days over an order to have communities surrender arms, some were feeling the government was lenient on one side,” a police source said.
In the elections on March 4, Kenyans will choose a successor to President Mwai Kibaki, who is not running again, as well as new lawmakers, governors and local officials.
The last elections in December 2007 were followed by the worst outbreak of violence Kenya has seen since independence, shattering the country’s image as a beacon of regional stability. The unrest killed at least 1,100 people and displaced more than 600,000.
Traditionally however, violence linked to elections has tended to take place before the actual polls.