Hundreds of armed raiders killed at least 38 villagers and torched more than 150 houses on Monday in the latest fighting between rival tribes in a dispute over land and water in Kenya's coastal region.
In an attempt to stem the bloodshed, President Mwai Kibaki introduced a dusk-to-dawn curfew in Tana River County where the attacks occurred and ordered the deployment of additional security personnel to the area.
"The government has... directed the declaration and maintenance of a dusk-to-dawn curfew among other measures... In the meantime, additional detachments of security forces have been sent to the area with immediate effect," Kibaki's office said in a statement.
"The killings of innocent women, children, men and security officials is a heinous crime and the perpetrators must be punished accordingly for their outright disregard for the sanctity of human life and property."
It was unclear how long the curfew would remain in place.
More than 100 people have been shot, hacked and burned to death in the last three weeks as the Pokomo and Orma tribes have fought one another in a deadly dispute over Orma-owned cattle grazing on land the Pokomo say is theirs.
Security forces were trying to disarm both tribes on Monday evening and Samuel Kilele, the provincial commissioner in Coast province, said police had arrested 15 people over attacks last week.
Earlier in the day, Kilele called for the military to be sent to the Tana Delta area as the police struggled to end the killing.
The land clashes and deadly riots in the port city of Mombasa following the killing of a radical Muslim preacher last month have stoked fears of more unrest along the coast ahead of a presidential election next March.
"We will soon recommend to the government to send military officers down there to help us restore order," Kilele said.
Jillo Dabacha, who chairs a community security group in the trouble zone, said about 300 attackers armed with spears, bows and arrows and guns had surrounded the Orma village and attacked a nearby police camp in a co-ordinated strike.
"They wanted to prevent the police from interfering with their attack on the village," Dabacha told Reuters by telephone.
Settled Pokomo farmers and semi-nomadic Orma pastoralists have clashed intermittently for years over access to grazing, farmland and water. The violence broke out again last month after the Pokomo accused the pastoralists of grazing cattle on their land and massacred more than 50 Orma villagers.
Awash with guns
The Kenyan Red Cross said the death toll from Monday morning's attack on Kilelengwani village was 38 people, including nine police officers, and that it was considering pulling its local staff out of the Tana Delta.
Kenya's Indian Ocean coast is a major tourist destination but many Kenyans accuse the government of a decades-long economic and political marginalization of the region, creating deep social divisions.
Zipporah Wamboi, a secondary school teacher in the Tana Delta, said there were often food shortages and very limited access to clean water.
"People drink from the swamps and the crocodile-infested Tana River. The plight of these people has been ignored for years now and something must be done quickly," Wamboi said.
Wamboi also said many in the area were armed.
"Many of us believe that there is a political instigation to this violence. This violence always (reaches) a high crescendo when the political temperatures start to take root," Hassan Omar, a lawyer and former commissioner at the Kenya National Commission for Human Rights, told Reuters.
Prime Minister Raila Odinga visited the area after an earlier attack but government efforts have failed to ease tensions.
Cattle rustling and clashes over grazing and farming land are relatively common between communities in arid areas of east Africa and often escalate into revenge attacks.
An influx of weapons across Kenya's borders, in particular from war-ravaged Somalia, has made the situation more violent.
-- Joseph Akwiri
writes for Reuters from Mombasa, Kenya. Additional reporting for Reuters by George Obulutsa in Nairobi and writing by Richard Lough.