At least 15 persons were killed when two suicide car bombers detonated themselves in Somalia's Galkayo town on Sunday, the police said."Two car bomb blasts targeted the local government headquarters," Xinhua news agency quoted a police official as saying.Heavy gunfire erupted after the explosions, witnesses said.The Al Qaeda-linked Al-Shabab group, which has been carrying a series of raids in Somalia, claimed the attack, saying it killed "dozens" of Puntland state soldiers.