The family of a woman knocked down by a Hong Kong truck driver in Shenzhen has accused him of kidnapping her four-month-old son, who she was pushing across the road in a stroller. Li Yun, 20, was hit by the Hong Kong-licensed truck, driven by Leung Koon-bui, at about 7am on Sunday. Leung allegedly fled the scene, leaving Li seriously injured. A witness said the truck ran over the stroller and dragged it away with the baby still inside. The baby was still missing yesterday. Shenzhen police said Leung returned to Hong Kong less than an hour after the accident. He later returned to Shenzhen and police are detaining him. Li, who was being treated for a fractured skull at Nanling Hospital yesterday, said: 'The truck suddenly appeared and then I was knocked down and lost consciousness.' Her mother-in-law, Wang Guizhen, said witnesses told her the truck did not stop. 'Many witnesses waved at the driver to get him to stop, but he ignored them and sped away,' she said. 'They even heard our baby cry in the stroller. It's definitely a case of the driver kidnapping our baby since the baby was alive at that moment.' Officers contacted Leung's firm in Shenzhen at about 10am on Sunday, demanding that he return to Shenzhen to assist in the investigation. Leung said he was not aware there had been an accident and found an empty stroller under his truck when he passed the Tanglangshan Tunnel on the Nanping Expressway. He said he pulled the stroller from beneath his truck and discarded it, according to Shenzhen police. They mobilised more than 100 officers to search for the baby and found the stroller, with blood on it, at 10pm on Sunday. Leung has been detained on hit-and-run charges. Li's mother-in-law holds out hope the baby is alive. 'We believe the baby is still alive and may have been hidden somewhere in Hong Kong by the driver,' Wang said.