At least 20 Syrian rebels were killed in a blast at a border crossing with Turkey Thursday, the Syrian Observatory for Human Rights said. The Britain-based monitoring group said it was unclear what caused the blast at the Atme crossing between Turkey and the northern Syrian province of Idlib, adding that around 20 people had also been wounded.
Turkey's state-run Anatolia news agency confirmed the blast left 20 people dead at Atme, adding that it took place during a "change of guard" among Syrian rebels in the area. Rebel fighters have been targeted at the crossing before.
The Islamic State group claimed responsibility for a mid-August suicide attack there that killed at least 32. The rebels killed on Thursday were among those participating in Turkey's Operation Euphrates Shield in neighbouring Aleppo province.
Ankara began the unprecedented cross-border operation on August 24, saying it was targeting both IS and the Kurdish YPG militia which Turkey considers a "terrorist" group.