Five people were on Sunday killed during an attack in Forole, Marsabit county.
Another six people were seriously injured in the attack which happened around 4am.
The attack was carried out by suspected militia from Ethiopia who fled.
It came hours after the census kicked off.
The attackers stole an unspecified number of cattle.
Marsabit police commander Steve Oloo said two children aged between 13 and 15 were among those killed.
