Four people were killed in the northern Kenyan town of Mandera, which borders Somalia, police said on Friday, in an attack blamed on Islamist group Al-Shabaab.
The four men, all non-Muslims who were not from the area, were attacked at a remote quarry on Thursday night, with some of them shot dead and others hacked with a machete.
"They were killed at the quarry during the attack," said regional police commander Mohamud Saleh. "We suspect Al-Shabaab and we are pursuing them."
A senior police source on the ground, speaking on condition of anonymity, said the group of more than 10 attackers "opened fire indiscriminately at the workers".
He said several others were injured.
National police spokesperson Charles Owino confirmed the killings.
"The attack was targeting non-locals and all those who died are not from here."
Owino said police had received reports of an impending attack and security was beefed up in the region, however "no one knew exactly where" the attack would be.
A major security operation was launched on Friday to track the attackers, believed to have fled to Somalia.
The Shabaab is fighting to overthrow the internationally backed government in Mogadishu but also regularly carries out attacks in neighbouring Kenya, which has troops in Somalia as part of an African Union force.
In its bloodiest single attack on Kenya so far, Shabaab gunmen raided a university in Garissa in April 2015 killing 148 people, most of them students, while in 2013 the group killed at least 67 people in an assault on a shopping mall in Nairobi.
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