The attack was carried out in an area popular with non-locals. Reuters
Militant Islamist group al-Shabab says it has killed six Christians in north-eastern Kenya in an attack aimed at forcing them out of the region.
The grenade and gun attack was launched on a residential block in Mandera town when people were sleeping, police said.
It was the latest in a spate of deadly attacks targeting Christians in the mainly Muslim region.
In December 2014, al-Shabab killed 38 non-Muslims at a quarry after separating them from Muslim workers.
A few months earlier, 28 people were killed after Muslim passengers were split up from the other passengers.
The attack happened as “planned” and was aimed at Christians in Mandera town, a radio station run by al-Shabab has reported.
The group wanted non-Muslims to leave what it regarded as Muslim areas, a spokesman told the BBC.
Mandera County commissioner Fredrick Shiswa said the militants had also targeted a telecommunication site, but this was done to divert the attention of the security forces from the “actual attack”.
“This must have been planned over a long period… It was executed with a lot efficiency,” Mr Shiswa said in a BBC interview.
Al-Shabab is loyal to al-Qaeda. AP photo
Sadiq Sharif, who was among 27 survivors, said al-Shabab raided the compound despite the fact that it was close to a police station in the middle of the town.
“However, I would like to thank the four local police reservists who rescued us. If it were not for them, no-one would have survived,” he told the BBC.
Analysis: Abdullahi Abdi, BBC Somali service, Kenya
Mandera borders Somalia, making it vulnerable to attacks from militants based there. The militants usually cross the porous border, carrying out deadly attacks on civilians and security agents before fleeing back.
In 2015, Kenya’s government announced that it would build a security wall along parts of the border to keep the militants out. But it is likely to abandon the plan because of strong resistance from Somalia’s government and border communities.
Its current focus is on recruiting more local Muslim police reservists and the strategy has had some success in curbing attacks. Muslims in the north-east increasingly see al-Shabab as a threat to their own interests, and are making a concerted effort to improve relations with Christians living there.
Many of the Christians are skilled workers from other parts of Kenya, making a vital contribution to hospitals and schools. The north-east is one of Kenya’s poorest areas and if they are driven out public services will worsen.
Al-Shabab is headquartered in Somalia and is affiliated to al-Qaeda.
The militants have been at war with Kenya ever since Kenyan forces entered Somalia in October 2011 in an effort to crush them.
Kenyan troops are now part of the African Union mission in Somalia fighting the group.
When al-Shabab killed 148 people in an attack on Kenya’s north-eastern Garissa University College in April 2015, the militants reportedly singled out Christians and shot them, while freeing many Muslims.