Somali militant group Al-Shabab militants have hijacked a bus in Kenya’s north, killing 28 non-Muslims on board after they had been singled out from the rest of the passengers.

The bus travelling to the capital Nairobi with 60 passengers was hijacked 50km from the town Mandera near Kenya’s border with Somalia.

“I can confirm … that 28 innocent travellers were brutally executed by the Shabab,” regional police chief Noah Mwavinda told AFP.

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The passengers were ordered off the vehicle, with the gunmen separating the travellers into groups of Muslims and non-Muslims.

The militants then boarded the bus again with the non-Muslims and tried to drive off, but the vehicle got stuck.

“So they executed their prisoners” before escaping back into Somalia, Mwavinda said.

Kenya’s Red Cross confirmed Saturday’s death toll in a tweet after its team arrived at the scene.

Some of the dead were public servants who were heading to Nairobi for Christmas vacation, police officers said.

Kenya has been hit by a series of gun and bomb attacks blamed on the al-Qaeda-linked al-Shabab militants since it sent troops into Somalia in October 2011.

Authorities say there have been at least 135 attacks since then, including the Westgate Mall attack in which 67 people were killed. Al-Shabab claimed responsibility for the attack in September 2013.

The terror group also said it was responsible for other attacks on Kenya’s coast earlier this year which left at least 90 people dead.