Rival Kikuyu and Maasai tribal fighters armed with machetes and spears clashed over scarce water supplies in central Kenya, killing at least 14 people in two days of fighting.
Thousands of people fled the fighting that broke out in Mai Mahiu, 37 miles north-west of Nairobi, said police spokesman Jaspher Ombati.
Scores were injured in the clashes and dozens of houses were burned, he said.
An Associated Press reporter saw fighters from both sides walking around Mai Mahiu with machetes, spears, bows and arrows.
At least 14 people were killed in the fighting before reinforcements arrived and restored order today, Ombati said, adding that tensions remained high.
The fighting started when Maasai herders destroyed pipes used to pump water from a river into 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.
A drought last year in Kenya dried up seasonal rivers important to cattle, goat and sheep herders, such as the Maasai. The drought also led to food shortages in parts of the country.