Kolkata, April 2 -- Security was beefed up inside the Indian Museum following a bomb threat emailed to the authorities. The security forces conducted thorough search inside the museum during Tuesday afternoon following the threats, sources said. A group that identify itself as "Group 1378" allegedly mailed to the Museum authorities that they would come at 1.20 pm on Tuesday and that explosives would be planted inside the iconic building so as to ensure a "mass killing." The Museum Indian is controlled by the Central Government and is manned by the Central Industrial Security Force. A similar threat was received by the authorities in the month of January. "Though similar threats were received earlier nothing has to be left to chances . so th...