At least 12 people were killed and 13 wounded when a suicide bomber exploded himself at the house of a pro-government leader in Afghanistan on Sunday, authorities said.The incident took place at the gate of the house of Malik Usman Shinwari, Xinhua news agency reported. A tribal leaders' meeting was underway at the building when the attack took place.Government official Attaullah Khogyani confirmed the causalities. No group has claimed responsibility for the attack.