Fighters linked to al-Qaeda executed 11 men they accused of taking part in massacres orchestrated by Syrian President Bashar al-Assad's forces, a video published online apparently showed.
A man whose face was covered in a black balaclava shot each man in the back of the head as they kneeled, blindfolded and lined up in a row.
The executioner said in the video: "The sharia court for the eastern region in Deir al-Zor (east Syria) has sentenced to death these apostate soldiers that committed massacres against our brothers and families in Syria."
The fighters shouted "God is great" as each man was shot.
ITV News cannot independently verify the authenticity of these video clips which were posted on a social media website and distributed by Reuters.
The Syrian deputy foreign minister told ITV News they were using 'new tactics' to fight rebel soldiers trying to overcome the Assad regime.
Although this week has been calmer than most, the relative silence was smashed by multiple artillery strikes across the city today.