NAIROBI, Kenya — A deadly attack on Christians in northeast Kenya was intended to drive them out of the region, a radio station run by the militant Islamic group al-Shabab has claimed.

The group said that its militants were behind a grenade and gun attack on a residential block in the town of Mandera, when people were sleeping, BBC News reports. The attack killed six people.

The group said via radio that the attack happened as planned and was aimed at Christians. A spokesman for the group told the BBC that the group wanted non-Muslims to leave areas it regards as Muslim.

Militants also attacked a telecommunications site, according to Mandera County commissioner Fredrick Shiswa, who said this was a diversion from the attack on the neighborhood.

Shiswa said the attack appeared to have been planned over a long period and was carried out with efficiency.

Mandera is on the border of Somalia, where the al-Qaeda affiliated group is based.

Many of the town’s Christians are skilled workers from other parts of Kenya who help contribute to hospitals and schools. Muslims not aligned with al-Shabab have sought to strengthen relations with Christians.

The militant group killed 148 people at Keya’s Garissa University College in April 2015, also reportedly targeting Christians.

Al-Shabab militants have fought against Kenya since a 2011 effort by the Kenyan military that entered Somalia to fight the group. Kenyan troops are among the African Union forces in Somalia to counter Al-Shabab.