News World A blast at a fireworks factory in China's Hunan province has killed 21 people and injured 61, prompting President Xi Jinping to call for a thorough investigation, state media is reporting. The blast in Hunan's capital city of Changsha, home to a hub for fireworks manufacturing, occurred on Monday around 4.40pm (0840 GMT), according to reports by CCTV and Xinhua. Videos on Chinese internet platforms showed thick smoke billowing from a large site with collapsed buildings and debris strewn around the area. Reuters could not verify the footage. Nearly 500 firefighters, rescuers and medical personnel attended the scene, according to the South China Morning Post. The blast happened at Huasheng Fireworks Manufacturing and Display Company, media said. Reuters could not find a telephone listing for the company to seek comment. The fireworks plant explosion on Monday in central China's Hunan Province has left 21 people dead and 61 others injured, authorities said Tuesday.…