challenges” as a monitor said the death toll has risen to 642 people. Eyewitnesses have accused government supporters of carrying out execution-style killings and video footage has emerged of mass graves.

The UK-based Syrian Network for Human Rights (SNHR) told CNN on Sunday that “non-state armed groups” that are loyal to Assad were responsible for the deaths of 315 individuals, which include 167 members of state security forces and 148 civilians. Government forces and affiliated groups were responsible for the deaths of at least 327 individuals, the independent monitoring group said, adding that this number includes “both civilians and disarmed militants.”

CNN can’t independently verify SNHR’s figures. CNN has reached out to the Syrian government for comment regarding the death toll. Syria’s interim president, Ahmad al-Sharaa, called for national unity Sunday as international alarm grew over the violence. Clashes reportedly continued overnight into Sunday but CNN was unable to determine the full extent of the unrest.

“What is happening in the country are expected challenges. We must preserve national unity and civil peace in the country,” Sharaa said at a mosque in Damascus he said he used to pray at two decades ago.