Two communities clashed at the border of Isiolo and Meru counties on Friday following the killing of a Borana boda boda rider.
Police said members of the Borana community ganged up to steal motorcycles belonging to their Meru counterparts when they learned one of their own had died.
"They began fighting each other, some stealing from shops and supermarkets and even throwing stones at motorists," an officer said.
"These people keep stealing motorcycles but there is nothing police are doing," a resident said, adding officers could not end the clashes.
Police officers lobbed teargas canisters and fired in the air to disperse residents who engaged them in running battles. They camped outside a mosque in Isiolo to maintain security.
Officers said the rider's killer wanted to steal his motorcycle in the attack on Thursday night.