Arshad Khan, political tehsildar of Bara region in Khyber Agency, said a group of people had assembled in a 'hujra' (guesthouse) at Dar Jumat Akakhel, a remote area close to the border with Afghanistan, when a huge blast occurred.
Nine persons, including three children, were killed and several others injured, he said.
Khan said a live mortar shell apparently exploded when one of the victims started to play with it. The identity of the victims could not immediately be ascertained.