At least 34 persons were killed and 21 others injured on Sunday after a bus collided with a truck in Afghanistan's Zabul province, police said."The accident took place along Kabul-Kandahar highway at around 5.00 a.m.," a senior police official told Xinhua news agency.The death toll was likely to increase as many of the injured were in critical condition, he added.Local officials said that the bus travelling from Kandahar to Kabul was carrying around 60 persons.