At least 52 people were killed in clashes on Thursday between several Islamist factions and Islamic State (IS) in the northern Syrian province of Aleppo, according to the Syrian Observatory for Human Rights (SOHR).The London-based NGO said that at least 40 opposition fighters from Syrian Islamist factions were killed, while 12 IS members were also killed in the clashes in Aleppo.Meanwhile, IS detonated a car bomb on the outskirts of the Syrian city of Mare, in northern Aleppo, on Thursday morning, according to SOHR.Clashes were ongoing in Mare and around the villages of Harjala and Dalha, also in Aleppo.IS fighters carried out the attacks coinciding with an offensive launched in Mare on Thursday morning, where they were able to conquer the towns of Sandaf and al-Harbal.