TEHRAN: A percussion bomb exploded in the restive southwestern Iranian oil city of Ahvaz late on Saturday evening but caused no injuries, the official IRNA news agency reported. People poured into the streets in panic after the blast, the agency said. “An initial investigation found the exploded object was a percussion bomb,” Khuzestan Governor Amir Hayat Moqaddam told IRNA, referring to the device designed to create more noise than damage. A little-known group campaigning for independence for Iran’s Arab minority claimed responsibility for Tuesday’s attacks in a Web statement.