BEIRUT: A car bomb near a checkpoint manned by Turkey-backed rebels in the northern Syrian town of Afrin killed 13 people including eight civilians Thursday, a war monitor said. “The car bomb exploded near the checkpoint at the entrance to the town where vehicles were gathering to be checked,” the Britain-based Syrian Observatory for Human Rights said. Turkish troops and their Syrian proxies took control of Afrin from Kurdish forces in March last year after a two-month air and ground offensive.