Officials said more than 620 people were injured in the blasts in the city's western suburbs as commuters made their way home. All seven blasts came within an 11-minute span, between 6:24 and 6:35 p.m..

There was some confusion about the number of dead and injured as information was compiled from hospitals and explosion sites in Mumbai, the west Indian seaport previously called Bombay.

"There still are bodies being recovered," said Pooja Saxena, with the International Federation of the Red Cross, speaking early Wednesday.

Witnesses reported body parts littering the railway tracks. TV news channels broadcast footage of bystanders carrying victims in driving rain to ambulances and searching through the wreckage for survivors and bodies. Confusion and panic was compounded when the local mobile phone network collapsed.

One person was arrested in New Delhi in police raids after the explosions, but there's been no claim of responsibility for the attacks.

Manmohan Singh, India's prime minister, held an emergency cabinet meeting and said afterwards that "terrorists" were behind the attacks. "I reiterate our commitment to fighting terror in all its forms," he said in a written statement.

US officials said suspicion fell on two Islamic terrorist groups whose focus has been on the disputed territory of Kashmir -- Lashkar-e-Tayyiba and Jaish-e-Mohammed.

The financial capital suffered similar serial blasts in 1993 that included an attack on the stock exchange, killing more than 250 people in what was then the worst terrorist attack in history.