Four people have died in a grenade attack on a government vehicle transporting exam materials in Lafey area, in Mandera.
Military Spokesman Emmanuel Chirchir said a rocket propelled grenade was thrown at a LandCruiser in Sino area.
Those who died were the principal of Lafey secondary school in Mandera district, the Lafey divisional district education officer, a former councillor and a mechanic.
Two homeguards who were escorting the victims survived the attacks.
This is the third grenade attack this week, after two other explosions rocked separate locations in Nairobi on Monday morning and evening.
The four casualties were among six people travelling to Mandera town early in the morning, in a Toyota Surf vehicle that belonged to the principal.
They were ambushed when they were about 50km from Mandera by militia who emerged from bushes and started spraying the car with bullets.
An administration police officer in Mandera said the homeguards jumped out of the vehicle firing back at the bandits, who responded by hurling the explosive device on the vehicle.
The two homeguards were said to have escape in a hail of bullets ad were reported to have sustained injuries.
The headmaster, the DEO and the councillor were said to have been well-known figures in Mandera town.
They had been driving to the town daily to pick exam papers since the tests began almost two weeks ago.
Confirming the incident, North Eastern Provincial Commissioner James ole Serian linked the attack to the Al shabaab militia group currently being pursued by the Kenya army inside Somalia.
He said security agents are pursuing the group across the border .
The PC said that a Provincial security committee had met following the incident and more police had been deployed along the porous Somalia border.
He said patrol will be intensified across the province so as to protect life and property of innocent mwananchi who he said are an easy prey to members of militia group.
He cautioned people visiting social places such as bars to be vigilant and report suspicious looking individuals to police.
The administrator said that a search will be conducted in the province to wipe out foreigners causing chaos in the name of retaliation.
The provincial boss cautioned residents to avoid traveling at night saying that the gang would use darkness as a mask to attack.
He directed the provincial administrators hold security meetings for the next three days to sensitize members of the public on security measures.
He advised travelers from Mandera County to use Mandera -ramu-elwaq and avoid mandera-lafey-elwak route as it was prone to militia attacks
Meanwhile, Police Spokesman Erick Kiraith described it as a “banditry attack” that happened about 110 km (70 miles) from Mandera town.
In a brief statement to newsrooms, Kiraithe said his officers are heading to the scene and will give more details in due course.
“We have received a report of a banditry attack in Mandera District about 110 kilometers from Mandera town involving a vehicle carrying government officials among others . The District Police Commander and his security team are proceeding to the scene , we shall give details in due course”.
Kenya sent hundreds of troops into Somalia on 16 October to attack al-Shabab, which is linked to al-Qaeda.
Al-Shabab has repeatedly threatened retaliatory attacks on Kenya.
On Wednesday, a man arrested after two grenade blasts in Nairobi, admitted in court to being a member of the group.
Elgiva Bwire Oliacha pleaded guilty to carrying out the attacks on a nightclub and bus stop.
One person was killed and 29 others were wounded in the attacks on 24 October.
Security has been stepped up in Nairobi since the blasts.