Indian Prime Minister Manmohan Singh has vowed that "no-one can make India kneel", a day after a series of train bombings in Mumbai killed 200 people.
Forensics experts are combing the bombed carriages for clues
In a TV address, Mr Singh said those affected by the rush hour attacks had responded with "courage and humanism".
The government says there are so far no leads, and it has avoided naming any particular groups as suspects.
Two Islamic militant groups fighting Indian rule in Kashmir have denied any involvement in the attacks.
Correspondents say the government has publicly adopted a cautious approach, saying only that "terrorists" are to blame.
"I urge each one of you to remain calm," the prime minister said. "Do not be provoked by rumours. Do not let anyone divide us. Our strength lies in our unity."
Mr Singh commended the work of police, firefighters and medics and said his country would not be cowed.
"No-one can come in the path of our progress," he said. "The wheels of our economy will move on.
"India will continue to walk tall, and with confidence."
Maharashtra deputy chief minister RR Patil told the state assembly the death toll had risen overnight, with 200 bodies now pulled from the wreckage.
Mumbai, formerly known as Bombay, is India's commercial heart and the bombers hit right at its bustling centre in the south.
But on Wednesday morning, the commuter trains, which carry six million people to work every day, were up and running again and crowded as usual with passengers.
"I will go on the train today again. I am not afraid of death," said Prashant Singh, a software engineer who was on the train that was bombed at Bandra station.
While the front pages of local newspapers carried stories detailing the terrible carnage, inside the headlines emphasised Mumbai's "invincible" spirit.
Correspondents also report long lines of Mumbai's minority Muslims queuing to donate blood to some of the 714 wounded in the blasts.
Meanwhile India's stock market confounded predictions, rising three percentage points on the morning after the bombings.
Group denies involvement
Police said they mounted a series of raids in the Mumbai area and detained suspects for questioning, but made no arrests.
Analysts suggest a powerful, possibly transnational group must have been behind the co-ordinated bombings, timed to go off at the height of the evening rush-hour.
The police chief of the state of Maharashtra - of which Mumbai is the capital - said the bombings bore the hallmarks of Lashkar-e-Toiba, a leading Pakistan-based militant group fighting in Kashmir.
But a spokesman for the group rejected suggestions that it had been behind the attacks, describing them as "inhuman" and "barbaric".
A second group, Hizb-ul-Mujahideen, also condemned the blasts.
'Infrastructure of terrorism'
The BBC's Geeta Pandey says that unlike in the past, when India has been quick to blame Pakistan or Pakistani-supported militants for attacks, Delhi has adopted a cautious approach.
But tensions became apparent on Wednesday, when a spokesman for the Indian foreign ministry accused Pakistan's Foreign Minister Khurshid Kasuri of an "appalling" attempt to link the bombings to the failure to resolve the dispute over Kashmir.
Spokesman Navtej Sarna also urged Pakistan to "dismantle the infrastructure of terrorism" on territory under its control.
Pakistan's foreign ministry later rejected the accusations in a statement, saying Mr Kasuri's remarks had been misreported and denying he had drawn a link between the bombings and the Kashmir dispute.
It insisted Pakistan was "in the forefront of international efforts to fight [the] menace" of terrorism.