Seven people were killed and several others wounded during a cattle raid in Turkana on Friday.
The incident occurred at a remote village in Kaptiri at dawn where bandits attacked a manyatta.
"The attack left seven people dead and we have others who have been wounded," a senior police officer told Capital FM News from Turkana. "We have been told of more deaths, but we are yet to confirm this."
Inspector General of Police David Kimaiyo said he had been briefed on the raid but did not provide further details.
"We had an incident of cattle rustling. We will give you more details once we get them," Kimaiyo said.
Cattle rustling and revenge attacks between rival groups leave dozens dead every year in the region, where guns are readily available.
In November, gunmen in northern Kenya killed 42 policemen in an ambush as they pursued cattle thieves.
The government has been accused for failing to conduct a meaningful disarmament exercise, particularly in northern Kenya where the illegal arms business thrives.
With less than a month to go until Kenya's general election, analysts are warning that widespread illegal gun ownership presents real risks to security.
The warnings come after a series of violent incidents, particularly between pastoral and farming communities fighting over water, grazing rights and other resources.
The Rift Valley experienced some of the worst violence after fighting erupted over the disputed presidential election in December 2007, leaving more than 1,300 dead across Kenya.
A 2012 study by the international monitoring group Small Arms Survey and the Kenya National Focus Point on Small Arms and Light Weapons indicated that between 530,000 and 680,000 firearms were held illegally across Kenya. While that was lower than the number recorded in a similar study 10 years ago, the figures showed a rise in two provinces - Western and Rift Valley.
The Kenyan government conducts a disarmament drive on an annual basis, and since the August attacks in Tana Delta, it has carried out two such exercises there.
But observers say these efforts have achieved little, and guns are still freely available in Tana as well as other parts of the country.
The 2012 arms report spoke of "a need to re-examine the effectiveness of government approaches to disarmament". It ascribed escalating demand for arms in the Rift Valley to the government's failure to provide adequate security, and to the particular vulnerability residents feel at election time.