Security beefed up at the Mantralaya building after a bomb threat call was received by the Disaster Management Control Room, in Mumbai on Sunday. (ANI) MUMBAI/NAGPUR: Mumbai Police personnel on Sunday conducted a search operation at the Maharashtra government secretariat here after a caller, later identified as a farmer from Nagpur district, claimed that a bomb was planted on the building, which turned out to be a hoax call, officials said. "Around 12.40 pm, the Disaster Management Control, Mantralaya, received a call from an unidentified caller claiming that a bomb was planted on the Mantralaya," Mumbai Police said in a statement.