The Syrian Network for Human Rights said armed groups and foreign fighters aligned with the government but not integrated into it were largely responsible for the sectarian violence.

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.

This past weekend’s sectarian violence was possibly among the bloodiest 72 hours in the modern history of Syria after 14 years of civil war — and it threatens to open an endless cycle of vengeance