At least 31 people have been killed and many others injured after an explosion involving a fuel tanker in western Afghanistan, officials say. The incident happened in the town of Azizabad, about 650km west of Kabul, in the Shindand district of Herat. The explosion, believed to have been an accident, hit a busy area of shops and restaurants on the road between Herat city and Kandahar. The death toll is expected to rise, a security official in Herat city said. The blast was so powerful, according to officials, that several building were destroyed. The tanker is reported to have been carrying thousands of litres of gas when it exploded around 1400 local time (0930 GMT). There are different accounts as to how it happened. General Ziauddin Mahrudin, the security commander for Herat, told the BBC it was caused by a fire in a welding shop near where the tanker had parked. An investigation is underway, but he said initial indications are that it was an accident. With limited medical facilities in the immediate area, many casualties have been taken to Herat, 100km to the north. Aid agencies in the region with medical expertise have been offering to assist. (BBC)