Seven police officers, a doctor and two other people have been killed in an ambush in Wajir, a town near the border with Somalia.
Authorities said four people escaped the Friday evening attack with minor injuries.
Gunmen attacked a Mandera-bound bus between Kutulo and Wargadud area in Wajir County around 5.30pm Friday.
The suspected Al-Shabaab militants stopped the bus and separated the passengers into two groups. The terrorists released the bus and executed the victims.
Officials said the bus was carrying 56 passengers at the time of the incident.
Wajir County Commissioner Loyford Kibaara said the officers, who belong to the Anti-Stock Theft Unit (ASTU), were on their way back to work when the Medina bus was ambushed.
Mr Kibaara said the identities of two of the victims are yet to be established.
Mr Kibaara further said that the four survivors managed to escape from the bus through the windows and ran for their lives when the terrorists struck.
He added that among the survivors were three police officers while one was a civilian.