Security personnel were thrown into a tizzy on Thursday after a telephone caller claimed that a bomb has been planted in the West Bengal secretariat Nabanna that also houses the office of Chief Minister Mamata Banerjee.
The call, however, proved to be a hoax, and one person was arrested from the city later, police said.
Sniffer dogs and bomb disposal personnel were pressed into service, as police officers, Intelligence Bureau personnel, members of the city police's Special Task Force and sleuths carried out a thorough search for hours in Banerjee's chamber, as also those of ministers and bureaucrats.
A telephone operator at Nabanna had received the call around 3 p.m.
The chief minister was then in her office chairing an important meeting.