KOTA, India, (Agencies) - Security was tightened at all major railway stations in Kota division of India and search conducted in trains after railway authorities received a letter that threatened with bomb blasts in three trains, on Sunday, reports The Times of India. The letter dated December 18, which the authorities of Kota railway station received Sunday, warned of bomb blasts in three trains on Christmas, railway officials said. They, however, did not disclose the names of the trains, which were the "targets". Following this, security was tightened at all major stations of the division and all trains passing through the region were searched. Additional forces of GRP, RPF and police were deployed at all major stations.