Gunmen on Friday attacked a passenger bus in south-western Pakistan, killing at least 18 people on-board and injuring eight others, officials and aid workers said. The incident occurred in the remote Turbat district of Baluchistan province, when gunmen on motorbikes ambushed the bus and then fled. Babul Khan of Edhi ambulance service told DPA "At least 18 people have been killed and more than eight injured in the attack." President Asif Ali Zardari and Prime Minister Raja Pervez Ashraf condemned the incident, according to state-run Pakistan radio.