NAIROBI, Kenya – Islamic extremists from Somalia killed 36 quarry workers in northern Kenya early on Tuesday, targeting non-Muslims in a similar way to an attack 10 days ago on bus passengers.

The killings happened in Mandera County near the border with Somalia and the attackers escaped, according to the country’s police chief. The Gunmen crept up on dozens of workers as they slept in tents around the quarry at about 1 a.m. (2200 GMT), On Tuesday a village elder at Korome, near the site of the attack close to the Somali border said.

The group al-Shabab, which has been battling for years to establish hard-line Islamic rule in Somalia, claimed responsibility for the killings.

Kenya’s police chief David Kimaiyo announced his resignation following the attack, citing personal reasons.

Kenyan President Uhuru Kenyatta named a former army general, Joseph Nkaisery, to replace him.

Public pressure had been mounting for the resignations of Kimaiyo and Interior minister Joseph Ole Lenku following the previous attack 10 days ago in which 28 non-Muslims were dragged out of a bus and shot dead by Islamic extremists.

The quarry attack also came hours after a hotel in Wajir, also in northern Kenya, was hit by a grenade and gunfire, killing one person and wounding 13, according to police.

Kenyatta convened an emergency session of his cabinet in Nairobi in light of the latest violence.

An al-Shabab spokesman said the quarry attack was in response to Kenya’s troop presence in Somalia. As with past attacks, al Shabaab militants said they were punishing Kenya for sending troops to join African peacekeepers battling the Islamists in Somalia. In a statement, it put the death toll at 40 people and called them “Kenyan crusaders”.

The Kenyan military was deployed to Somalia in October 2011.

Since then, Kenya has experienced a series of explosive and gun attacks blamed on the militants.

Statement by NSC Spokesperson Bernadette Meehan on Al-Shabaab Attacks in Kenya

The United States strongly condemns yesterday’s attacks in Wajir and Mandera counties in Kenya as well other recent attacks by the terrorist group al-Shabaab targeting innocent civilians. We extend our deepest condolences to the families and loved ones of the at least 38 individuals killed yesterday. The United States will continue to support Kenya and our regional partners in combating terrorism and violent extremism and protecting human rights.

Story compiled with information from Reuters and The Associated Press.