Kikuyu and Maasai tribal fighters armed with machetes and spears clashed over scarce water supplies in central Kenya, killing at least 16 people in two days of fighting, police and an aid worker said.
At least 14 people had died in the clashes that broke out on Saturday in Mai Mahiu, about 60km northwest of Nairobi, said police spokesman Jaspher Ombati.
Later Monday two men died from injuries sustained in the fighting over the weekend, said Tuttah Ochieng of the Roman Catholic Church's justice and peace commission.
Thousands of people have fled the fighting since Saturday, said Ombati. Scores were injured in the clashes and dozens of houses were burned, he said.
The fighting intensified on Sunday when both Kikuyu and Maasai tribal fighters put up roadblocks, stopping minivan taxis and attacking commuters.
A reporter saw seven people pulled from vehicles and killed by fighters using machetes, spears, bows and arrows. Injured commuters were rushed to the hospital.
At least 14 people were killed in the fighting before reinforcements arrived and restored order on Monday, Ombati said, adding that tensions remained high.
The clashes were unusually deadly, though fights over water are common in Kenya, two-thirds of which is either arid or semiarid land.
The fighting started Saturday when Maasai herders destroyed pipes used to pump river water onto farms belonging to Kikuyu. The Maasai said the irrigation scheme denied them water for their livestock, Ombati said.
In retaliation, Kikuyu farmers attacked the Maasai, sparking the clashes, he said.
Hundreds of people, mainly Kikuyus and including children, were seen arriving on Monday at Kigecha, a shopping center about 10km from Mai Mahiu. Some had walked to the center, while others arrived on donkeys. Maasai fleeing the fighting went mainly to Suswa, 40km south of Mai Mahiu.
A drought last year in Kenya dried up seasonal rivers used by herders to water their cattle, goat and sheep.
The drought also led to food shortages in parts of the country.