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.

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.

The UN human rights office has verified the killing of 111 civilians in the coastal region, but says the actual figure is far higher.

A war monitoring group said more than 1,000 were killed in revenge attacks and clashes between Syrian security forces and loyalists of ousted President Bashar Assad.

Entire families including women and children were killed in Syria's coastal region as part of a series of sectarian killings by rival groups during an insurgency by Bashar al-Assad loyalists, the U.N human rights office said on Tuesday.