Kenyan Interior Minister Joseph Nkaissery said the motive is unclear. But al-Shabaab through its radio station in Somalia said they were responsible.
“The attack is part of a series of attacks targeting the Northern Frontier District region under Kenya's occupation,” said al-Shabaab's radio Andulus.”The Mujahideen forces who carried out the attack safely returned to base.” Kenya's northern and eastern region border Somalia and a significant number of inhabitants there are Kenyan-Somalis.
Al-Shabaab has been attacking Kenya since Kenyan troops were deployed to Somalia in Oct 2011 to fight the militants.
Police statistics show that 312 people have been killed in al-Shabaab attacks in Kenya from 2012 to 2014.
On Friday the militants claimed responsibility for attacking the convoy of Mandera County Governor Ali Roba in which four people died.
Al-Shabaab carried out large-scale attacks in Mandera last year. The militants hijacked a bus and singled out 28 non-Muslims forcing them to lie on the ground before shooting them dead.
Ten days later the 36 non-Muslim quarry workers were killed by the extremists.
On Wednesday four men - one Kenyan and three Somalis - were charged in a court in Nairobi with the killings of quarry workers.
