Mumbai authorities on high alert after an email threat warns of bomb blasts at the airport, Mayor office, and actor Amitabh Bachchan bungalow. Authorities in Mumbai were placed on high alert on Thursday morning following an email threat warning of bomb blasts across the metropolis, including at the airport, Mayor’s office, megastar Amitabh Bachchan’s bungalow ’Jalsa’ and a Punjab National Bank branch, an official said.The official said the email, sent at 10.