A Kenyan official says 12 people were killed in an extremist attack targeting non-Muslims in Mandera County near the Somali border.

Mohamed Saleh, Mandera's regional commander, said Tuesday that gunmen from Somali -based extremist group al-Shabab are suspected of carrying out the attack on the Bisharo Guest House.

Al-Shabab has vowed retribution on Kenya for sending troops into Somalia since 2011 to fight the militants who are waging an insurgency against Somalia's weak, Western-backed government. Kenyan security forces have managed to stop the wave al-Shabab's attacks in major cities in Kenya that have killed hundreds.

However, Mandera County remains a volatile area. Al-Shabab militants hijacked a bus in Mandera on November 2014, and killed 28 non-Muslims on board. In December 2014 they killed 36 quarry workers.