Armed groups killed entire families, including women and children, during an outbreak of sectarian violence in Syria last week, the United Nations human rights office said on Tuesday.

Armed groups loyal to Syria’s interim government have carried out mass executions as part of a campaign described as “cleansing,” according to CNN, citing eyewitnesses and video footage. The violence has escalated into large-scale killings in coastal regions under the control of the Syrian military administration.

The killings occurred in the heartland of Syria’s Alawite minority, escalating after a nascent insurgency formed against the Sunni Islamist government.