Gunmen have killed some 36 quarry workers near the north Kenyan town of Mandera, aid workers and officials say, the BBC reports.
The attackers separated Muslims from non-Muslims and shot the Christians dead, residents said.
Earlier, one person was killed in a bar popular with non-Muslims in a neighbouring district.
Islamist militants from the Somalia-based al-Shabab group killed 28 people in an attack on a bus targeting non-Muslims in the same area last week.
The attack on the quarry workers took place early on Tuesday. Witnesses said the victims were caught after midnight, while sleeping in their tents at the quarry.
A local police chief said the assailants targeted non-Muslim workers at the quarry in Kormey, 15km (nine miles) from Mandera town.