A mysterious letter threatening to trigger multiple bomb blasts in different places of the city, including the Raj Bhawan and the Chief Minister's residence, threw the police into tizzy and prompted them to step up security around vital installations.
The letter, received by Churchgate railway station master eight days ago, was written in Hindi and posted from Kanyakumari in Tamil Nadu, the police said.
The letter claimed explosives have already reached three different locations in the metropolis and five to six persons had been given the responsibility to execute the blasts either on November 14 or November 28.
The letter claimed explosions would occur at Vidhan Bhavan, Governor and Chief Minister's residences, RBI, iconic locations like Nariman Point, Juhu Beach, railway stations CST and Dadar, the police said.
It also mentioned the landmark Taj Mahal and Oberoi hotels in South Mumbai and Central Hotel in suburban Kalina as the targets, they said.
The letter has named two persons Arvind Singh Arora and Bhupinder Singh Arora who it says have hidden explosive material, including RDX, near Bhabha Farid Institute of Technology in Dehradhun in Uttarkhand.
Though not ruling out the possibility of the letter being a prank, the police said vigil has been strengthened.