Bombs exploded on packed commuter trains and stations in India's financial hub, Mumbai, today, killing over 160 people and wounding hundreds, officials said.
There was no immediate claim of responsibility for the seven bomb explosions that took place within about 10 minutes during evening rush hour.
But suspicion was likely to centre on Muslim militants fighting New Delhi's rule in disputed Kashmir, who have been blamed for several bomb attacks in India in the past.
"The death toll is 163 and around 460 people have been injured," a police inspector said.
"We are not sure if it is RDX or not," city Police Commissioner A.N. Roy said, referring to the possible use of high-powered plastic explosives.
Commuters fled suburban rail stations in panic after the explosions and mobile phone lines were jammed.
Hundreds of dazed passengers walked along the railway tracks. Television showed twisted rail carriages and people in torn, blood-stained clothes carrying the dead and wounded on stretchers as steady monsoon rain fell.
A policeman was shown carrying two white, blood-stained bundles of what appeared to be body parts.
"The blasts happened when the trains were most crowded," D.K Shankaran, chief secretary of the state of Maharashtra, of which Mumbai is the capital, said.
At peak hours, each nine-car passenger train in Mumbai carries over 4,500 people, about three times the rated capacity.
Prime Minister Manmohan Singh called for calm and Sonia Gandhi, leader of the ruling Congress party, expressed her grief.
"I urge the people to remain calm, not to believe rumours and carry on their activity normally," Mr Singh said in a statement, calling the explosions a "shameful act".
The United States called the bomb attacks "senseless acts of violence". Pakistan, the EU, France and Britain also condemned the explosions.
At the city's Sion hospital, relatives were frantically looking for friends and relatives. Scores pored over a board displaying a list of injured.
The blasts occurred on five trains and at two stations in Mumbai's western suburbs, which are linked to the downtown office and business areas mainly by an overground rail network that is used by some 6.5 million people each day. Railway authorities suspended all suburban train services in the city after the blasts.
Dazed survivors with wounds from injuries to heads, legs and hands waited at railway stations, with little sign of any emergency medical aid. "We heard a loud blast in one of the train compartments.
When we rushed there and looked, we saw people with severed limbs and grievous injuries," one witness told the CNN-IBN news channel, standing in a blood-spattered coach. "There were no police or railway people to help."
The first attack took place at 6.24 p.m. (1154 GMT) with the others following in quick succession. "Incidents had taken place in the space of 10 minutes. It appears to be pre-planned," Anil Sharma, chief security commissioner of Western Railway, told CNN-IBN television channel.
The Mumbai blasts came just hours after suspected Islamist militants killed seven people, six of them tourists, in a series of grenade attacks in Indian Kashmir's main city, Srinagar, police said, the most concerted targeting of civilians in months.
Kashmir has been split between India and Pakistan since shortly after the two countries gained independence from Britain in 1947, but both claim it in full. Pakistan's Foreign Ministry issued a statement saying that President Pervez Musharraf and Prime Minister Shaukat Aziz strongly condemned the "terrorist attack" in Mumbai.
Mumbai, a metropolis of about 17 million formerly known as Bombay, has been hit by bomb blasts in the past decade.
More than 250 people died in a string of bomb explosions in the city in 1993 for which authorities blamed the city's underworld criminal gangs.