The latest incident took place on Thursday morning at Chongqing’s Hongqiaohegou subway station.Local rail authorities said that a woman had brought her four-year-old son and three-year-old daughter into the station, and left them unsupervised in the ticketing hall.The boy was playing with the handrail at a nearby escalator when he fell. His chest was wedged between the bottom of the handrail and the ground.