Turkey’s prime minister vowed Sunday his country won’t be drawn into Syria’s civil war, despite twin car bombings the government believes were carried out by a group of Turks with close ties to pro-government groups in Syria. The bombings left 46 people dead and marked the biggest incident of violence across the border since the start of Syria’s bloody civil war, raising fears of Turkey being pulled deeper into a conflict that threatens to destabilize the region. Syria has rejected allegations it was behind the attacks. But Turkish authorities said Sunday they had detained nine Turkish citizens with links to...