ANKARA (Reuters) - At least four people were killed in a Turkish-controlled region of northern Syria on Thursday when a car bomb detonated at a checkpoint in the border town of Ras Al Ain, according to a Turkish official and a war monitor. The governor’s office in the Turkish town of Sanliurfa identified the dead as two Turkish police gendarmes and two members of local Syrian security forces. It blamed the blast on the Syrian Kurdish YPG, which Ankara views as a terrorist group. The Syrian Observatory for Human Rights, a UK-based war monitor, put the total death toll at 12, including seven Syrian fighters, two Turkish security personel, two civilians and one unidentified victim. Turkey, which is allied with some Syrian rebel groups opposed to Syrian President Bashar al-Assad, seized control of the town last year in an offensive to push back YPG fighters from the border.