Karachi, Aug 15 : Twelve members of an extended family, all women and young boys, were killed and several others suffered burn injuries after a grenade was hurled at a mini-truck on the outskirts of Karachi, the media reported on Sunday. A senior police officer told Dawn news that the attack on Saturday night was an act of terrorism. He said personnel from the Bomb Disposal Squad had found the lever of the grenade (at the crime scene) and confirmed that a Russian-made device had been used in the attack. The incident occurred in the Baldia area within the limits of the Madina Colony police station. "We are investigating the incident from different angles to ascertain whether the perpetrators were terrorists from some ethnic group or an extremist group," said the official Karachi police chief Imran Yaqoob Minhas told the media that the aspect of personal enmity was also being probed as all victims came from the same family. The family originally hailed from Swat. Local police and the Counter-Terrorism Department are both investigating the incident. Senior CTD official Raja Umer Khattab, who examined the spot, said initial probe revealed that the attackers were riding a motorcycle and that the grenade had exploded before falling into vehicle. Karachi South Zone DIG Javed Akbar Riaz told Dawn that the truck was carrying 20 to 25 people who were returning from a marriage ceremony. /IANS