A constable at Engineer AP post fired nine times at his boss, killing him at work, following a heated argument on Thursday.

The officer shot the sergeant in the chest during the midnight incident in Kinangop, Nyandarua County.

A source said the two had been working together for some months but had differed on several occasions.

"The constable used his G3 rifle to shoot his boss," the source said.

Nyandarua South sub-county commissioner Naomi Mwangi said the two were working when the argument ensued.

"The sergeant had been going around supervising his juniors when he met the suspect...he died at the scene," Mwangi said on phone.

The adminstrator said officers took the constable to Engineer police station and the body to a mortuary.

Investigations were launched.