Five people were killed on Friday when suspected Somali bandits raided a trading centre at Duse in Garba Tula subcounty, Isiolo.
It is believed that the armed gang of about 30 was from Garissa county.
A woman and three of the attackers were killed at the scene of the dawn ambush 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.
Rutto praised Kenya Police Reservists for responding quickly and said they were pursuing the bandits who escaped.
He said four of the reservists were seriously injured but were rushed to Maua Methodist Hospital for specialised treatment.