Gunmen shot and killed seven people and torched a lorry they were using in an attack in the Elle Dimtu area of Moyale, Marsabit county.
The area is along the Kenya-Ethiopia border.
Two other people were injured in the attack that happened on Monday night, police said.
Eastern regional police commander Charles Naibei said they are yet to establish the motive.
“We lost five people on the spot and I am told there could be more casualties,” he said.
He said the victims were transporting food from the border town to other parts of the country when they were ambushed.
The attackers shot at the lorry before setting it on fire. Two who survived ran out and hid in the thicket.
Former treasury Cabinet Secretary Ukur Yatanni blamed a militia from a neighbouring country for the attack.
“The sad incident where suspected militia from a neighbouring country ambushed a truck near Forole of Marsabit county, killing 7 persons and burning the truck needs an urgent response. We appeal to CS Interior to deploy more security personnel to protect these border communities,” he said.
Tension rose in the area amid calls on the locals on security agencies to address the menace.
Police said they had sent more teams to the area to address any more threats in the coming days.
It is the second such attack in two weeks which has so far claimed several lives including that of a policeman.
On August 1, a police officer was killed and three others including a civilian sustained serious injuries when an unknown number of gunmen launched an attack at a checkpoint in the Sessi area of Moyale town, Marsabit County.
Officials said the incident happened at the roadblock leading to the main Kenya-Ethiopia border.
A civilian woman believed to be a revenue clerk with the county government, was also critically wounded in the attack, which was carried out by suspects armed with grenades and assault rifles.
The attackers arrived on board a motorcycle and opened fire at the multi-agency team that was manning the roadblock leading to the Ethiopian border.
Police and witnesses said the attackers also lobbed two grenades at the team but they did not detonate.
The motive of the attack is yet to be known, police said.
Police suspect the attackers could be smugglers or terrorists who are trying to find a footing in the area.
They could also be criminals from the neighbouring country, police say.
The Moyale-Marsabit highway is one of the main routes used by human and drug smugglers.
The route, according to police is also a haven for terrorists trying to reach Isiolo and Nairobi.
The roadblocks mounted on the route have helped tame many crimes including terrorism.
Constable Collins Mutai succumbed to the injuries while receiving treatment at Moyale Sub-county Hospital following the attack.
Police said two undetonated grenades were recovered at the scene and later detonated by officials from the Kenya Defence Forces (KDF) who also responded to the incident.
The attackers, who fired indiscriminately at the multi-agency team manning the border point, left the victims with critical wounds.
Police believe the attackers were out to send a message to the security teams there.
But police say they will intensify their operations to address cases of drug trafficking, human trafficking and terrorism among others.
The roadblocks have helped to tame many crimes in general hence the attack.
Drug dealers get their products from Ethiopia and use Kenya as a transit route.