At least seven persons were killed in a major fire that broke out on the 13th floor of a multi-storeyed building in Kolkata's Strand Road area on Monday evening.Among the dead, four were fire brigade officials, an assistant sub-inspector (ASI) of Kolkata's Hare Street police station, a railway official and a security person, sources said. Two persons still remain missing in the incident.According to sources, the name of four fire brigade officers are -- Girish Dey, Biman Purokayet, Gaurav Baij, Aniruddha Jana. The ASI has been identified as Amit Bhawal."It is an unfortunate incident. At least seven people were killed in the blaze, including four fire brigade officers and an ASI of Hare Street police station. Two railways officers were also killed in the fire," West Bengal fire services minister Sujit Bose said.At least 15 fire tenders were rushed to the spot to bring the situation under control.The incident took place at New Koilaghat building on Kolkata's Strand Road. The building housed offices of the Railways.West Bengal Chief Minister Mamata Banerjee reached the spot around 11 p.m.Former Kolkata Municipal Corporation mayor and chief administrator Firhad Hakim also reached the spot to take a stock of the situation. The cause of the fire at the New Koilaghat building is yet to be confirmed, police said.The incident stopped the online booking of tickets in all zones of the Eastern Railway as the building, which caught fire, had a computerised ticket booking centre on its ground floor.