Dan Juma, the acting deputy director of the Kenya Human Rights Commission, told a New York Times correspondent in Nairobi said it was very suspicious inter-tribal rioting began when the results were announced.

"It wasn't like people just woke up and started fighting each other," Juma said. "It was organized."

A police source who asked not to be identified also said there was evidence of planning, such as a 9-foot ditch created by an earth mover severing a road and, therefore, police access. He said elsewhere, a large roadblock had suddenly sprung up.

"You don't move 10 tons of concrete on your back," the official said. "This is a full military operation."

The fighting is between the Kikuyus, Kenyan President Mwai Kibaki's ethnic group, and the Kalenjins, many of whom are loyal main opposition leader Raila Odinga. Along with international monitors, Odinga claims there was widespread vote rigging that returned Kibaki to power.