The Pokomo and Orma tribes have long clashed over water and land resources in the area, but fighting has increased since August, resulting in the deaths of 116 people.
Phyllis Muema, executive director of the Kenya Community Support Center characterized the latest attacks as massacres, The Guardian reported Thursday.
"The level of killing shows very clearly that this is not just a resource-based conflict. ... The sophistication of the arms they are using indicates that they have acquired them, we suspect, from neighbouring Somalia," Muema said.
Officials from Human Rights Watch said they suspect the heightened violence may be incited by local politicians hoping to win posts in next year's elections.
"Members of both communities, including victims of the attacks, told Human Rights Watch that area politicians who hoped to win seats in next year's elections were involved in the violence on both sides and that the villagers had informed the police about their suspicions," the group said.