Four army officers died instantly on Sunday night when the vehicle they were traveling in skid, hitting an oncoming car in Matunda, along the notorious Subuiga-Isiolo road.
The three men and one woman on training at the army's School of Infantry were heading to camp when their driver lost control and swerved at high speed.
The Nissan Note car was then hit by an oncoming saloon car, completely wrecking its left side, killing the occupants on the spot.
The other motorist was driving towards Meru town together with his wife and their two children. The four suffered injuries.
Buuri Police Boss Joseph Obara said Mr Simon Kobia, a former Meru County director of communications, his wife Elizabeth Syengo and their two children were admitted to Kiirua Mission Hospital.
He said the four sustained various injuries but were in stable condition.
The police boss said the vehicle ferrying the army officers was speeding and the driver could have lost control due to the loose chippings along the road which is under rehabilitation.
The three-kilometre stretch has seen multiple accidents occur due to the loose chippings.
Residents said about 10 people have lost their lives on the road in the last three months.
The bodies of the dead were taken to Kiirua Mission Hospital mortuary.