Al-Qaeda fighters killed the leader of a rival Islamic brigade in a twin car bombing near Syria's northern city of Aleppo, an attack likely to further exacerbate militant infighting .
Fighting was likely to be exacerbated further after Islamic State fighters undertook a twin suicide bombing that killed 26 people on Saturday, including the military leader of a militant group.
The attack targeted the base of rivals, the Tawheed Brigades, and killed commander Adnan Bakkour, said the opposition observatory.
The Al-Qaeda linked ISIL also killed another prominent commander of another rebel brigade, said analyst Charles Lister of the Brookings Doha Center.
Lister said the extremists killed Abu Hussein al-Dik of the powerful Suqour al-Sham, showing that the Islamic State was targeting key headquarters, "strategic checkpoints and senior influential commanders".
Also today, a group that supports militants posted a video to social networks showing a fighter beheading another man as adults and children gathered to watch. In the video, adults cheer as the fighter cuts the other man's head off with a small knife. The beheaded man's hands are tied, and it isn't clear if he was alive while he was being beheaded.
Photos of the body and severed head were also posted to a separate Instagram account by a supporter of the Al-Qaeda linked Islamic State. The photograph showed another decapitated body nearby.