BEIJING, April 13 (Reuters) - Four people were killed in a Chinese expressway pile-up involving 52 vehicles in morning fog on Friday, Xinhua news agency said. The accident happened on the Yongchuan section of the expressway running between Chengdu, capital of the southwestern province of Sichuan, and neighbouring Chongqing. An "unclear number" of people were injured, Xinhua added, saying an investigation was under way.
