Suspected Somali bandits raided a trading centre at Duse, Isiolo County and killed five people on Friday.
Four Kenya Police reservists were seriously injured during the incident but were rushed to Maua Methodist Hospital for specialised treatment.
They were responding to alerts of the dawn attack.
Reports say the attackers were from Garissa county.
A woman and three of the attackers were killed at the scene and the fifth person a short distance away.
Garba Tula subcounty commissioner Kipchumba Rutto said the bandits attacked at about 4.30am.
He said nothing was stolen but warned that they were out to kill and cause fear.
Tension has been high in the area following clashes between Somalis and Boranas over pasture and water.
The fighting has lasted about three months.
Photo: Armed GSU officers during a past operation. Courtesy/allafrica.com