At least 21 people were killed and more than 30 others injured when a bus collided with a truck in the southern Afghan province of Zabul Thursday, police said.The crash occurred at Kakarano Chine in the provincial capital Qalat, along the Kabul-Kandahar highway at around midday, deputy provincial police chief Ghulam Jiliani Farahi told Xinhua news agency."Nearly all 50 people aboard the passenger bus were affected as a result of the accident. A total of 21 people were confirmed dead and over 30 others were wounded. All casualties were shifted to hospitals in Qalat city," the official said.The bus was travelling to Kabul when the accident took place.Afghan officials blame reckless driving for most traffic incidents, saying such careless driving on congested roads and highways is the main cause of road accidents in the country.