The Prime Minister, Dr Manmohan Singh, spoke to the Maharashtra Chief Minister, Mr Prithviraj Chavan, soon after reports of serial blasts in Mumbai.
He told the Chief Minister to keep him posted on the developments.
The Home Minister, Mr P. Chidambaram, held a high-level security meeting.
The National Security Guard (NSG) was flown to Mumbai from Delhi after news of serial blasts at Opera House, Dadar and Jhaveri Bazar.
Even as television media were commenting on the terror links, Mumbai Police Commissioner was quoted as saying it was unwise to comment on suspects before investigation was over. South Mumbai MP and Minister of State for Communications and IT, Mr Milind Deora, appealed for calm, and asked people to avoid rumours and speculation, even as he headed to Mumbai.
The Pakistani President, Mr Asif Ali Zardari, and the Prime Minister, Mr Yousuf Raza Gilani, were quick to condemn the blasts.