An officer based at Makongeni police station died after he accidentally shot himself on the thigh while manning a road block last night.
Constable Samwel Ndirangu was rushed to the Metropolitan hospital in Buruburu where he died at around 9:45 p.m.
Doctors say what caused the death was loss of excessive blood.
Preliminary investigations have ruled out suicide as police launch quest into death.
The body has been transferred to Chiromo Funeral Parlour for postmortem.