PATNA: Four teenagers died and another was seriously injured when they were hit by Jogbani-Danapur Vande Bharat Express (26301) while crossing railway tracks in Purnia district early on Friday morning.Sources said the railways has started a detailed investigation into the accident. Preliminary probe suggested that the victims, between 13 and 15 years of age, might not have noticed the high-speed train approaching due to low visibility around 4.40am when the tragic incident happened.According to the initial reports, the victims were returning home after attending a Durga Puja fair, when the train, on way to Danapur, hit the boys between Kasba and Purnia stations under Northeast Frontier Railway (NFR), said Purnia station superintendent M Kumar, adding they were crossing the railway tracks on foot. Three of them died on the spot while one succumbed to his injuries on way to hospital.According to Purnea Junction RPF inspector S A Khan, the deceased teenagers were identified as Sintu Kumar (15), Jigar Kumar (13) and Shyamsundar Kumar (15), residents of village Thakurpatti under Jankinagar police station in Purnia district, besides Rohit Kumar (15) of village Chandanpur Bhangha in the same area. Injured Kuldip Kumar (14), a resident of village Rampur Tilakboy, is undergoing treatment at Purnia govt hospital.Police would record the statement of the lone survivor soon, said Khan.According to the NFR sources, both the Govt Railway Police (GRP) and Railway Protection Force (RPF) reached the site shortly after the incident. The bodies of the deceased were sent for postmortem and their parents were informed about the tragic incident, sources said.The NFR officials have also issued a warning to people in general to use designated crossings and avoid walking on the tracks, especially during night and early morning hours.