The powerful bomb exploded in the middle-class district of Bowbazaar shortly after midnight. Two apartment blocks collapsed, trapping scores of people in the rubble. More than 40 people had been brought dead to hospital and scores were injured.
Both buildings caught fire after the explosion, and at least 10 fire engines spent more than two hours fighting the flames. Bowbazaar is in the centre of Calcutta, a crowded trade and residential district surrounded by the city's main gold market and furniture market.
The police headquarters and Writers' Building, the headquarters of the state government of West Bengal, of which Calcutta is the capital, are close to the district.
At least 125 people lived in the two apartment blocks,the Press Trust of India reported. Two nearby buildings were also on fire with people caught inside. The blast was powerful enough to be heard 3 miles away.
Earlier, the US had warned India that the terrorist bombers who set off a chain of explosions last Friday in Bombay, killing more than 250 people and injuring 1,300 others, may strike in the capital, New Delhi.
The US State Department informed New Delhi it had received information indicating 'there may be a heightened threat at this time of additional acts of terrorism centred in New Delhi'. Washington is urging Americans to postpone travel to India. US bomb experts will help Indian authorities sift through the rubble of Friday's 11 blasts, looking for clues that might tie in the plastic explosives used in Bombay to the device that last month damaged New York's World Trade Center.
In Bombay, police uncovered a possible link between the bombers and one of the city's most powerful underworld gangs, led by Dawood Ibrahim, an Indian Muslim operating out of Dubai. Police identified two suspects who may have carried out out the bombing of three Bombay hotels. The two men, wanted for murder, extortion and drug smuggling, were tracked to a flat on Monday and surrounded by police. But they shot their way out of the police ambush.
Bombay police said that as many as 50 bombers may have been involved in Friday's wave of explosions across the city. On Monday, two motor-scooters loaded with plastic explosives were defused by police in a crowded bazaar of diamond merchants. The Home Minister, S B Chavan, said in parliament that the blasts were the work of 'some foreign country acting through their local agents'. Many Indian politicians have accused Pakistan of collusion in the bombing, but Islamabad denies this.
It is not clear why a Bombay criminal gang would help a foreign power set off bombs in India's financial capital. One possibility is greed: over recent years Bombay's underworld chiefs have earned fortunes smuggling gold, electronic goods and foreign currency into India from the Gulf states. But now, with economic reforms having stripped away India's heavy customs duties, the gangs' revenue has fallen drastically. Drugs and extortion are their only income.
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