There has so far been no claim of responsibility for setting off three near-simultaneous improvised explosive devices (IEDs), which were packed with ammonium nitrate during evening rush hour on Wednesday, killing 18 people. The bombings were the biggest attacks on Mumbai since the 2008 assaults killed 166 people, raised tensions with nuclear rival Pakistan, and left a city on edge. JEWELLERY TARGETS 
 
 The blasts came as beleaguered Prime Minister Manmohan Singh struggles to get past a series of corruption scandals and a resurgent opposition that has led to policy paralysis in Asia's third largest economy. Visiting some of the attack victims in Mumbai hospitals, the prime minister vowed those responsible would be tracked down. Any suggestion of attributing blame for the latest bombings to Pakistan-based groups would complicate a fraught relationship between the two countries, and further unravel Pakistan's ties with the United States. 'All leads followed' 
 
 No group has said it planted the bombs but suspicion among some officials and analysts has fallen on the Indian Mujahideen, a group which has claimed to have carried out similar attacks in the past. "There was no intelligence regarding a militant attack in Mumbai. That is not a failure of intelligence agencies," Home Minister Palaniappan Chidambaram told a news conference. "[We] know that perpetrators have attacked and have worked in a very, very clandestine manner, maybe a very small group that has not communicated with each other." He said it was too early to point the finger at a particular group, but said the "coordinated terror attacks" could be in retaliation to a number of plots recently stopped by police or arrests, including from the Indian Mujahideen. Those who made them had prior training," Home Secretary Raj Kumar Singh told reporters. He described the blasts as a "a co-ordinated attack by terrorists" as they occurred within minutes of one another. Continue reading the main story Mumbai attacks April 1993 - Serial bomb blasts kill 257 people and about 700 injured 
 
 2003 - Four bomb attacks, including twin blasts on 25 August which killed 52 people 
 
 July 2006 - More than 180 people killed and hundreds wounded in seven orchestrated blasts on commuter trains 
 
 November 2008 - gunmen target six locations in Mumbai killing at least 165 people in a series of co-ordinated attacks 
 
 The biggest explosion occurred at the Opera House business district in the south of the city, in an area known as a hub for diamond traders. One witness said he had tried to help by getting the wounded onto motorbikes to take them to hospital. Another blast, described by the authorities as low intensity, hit the Zaveri Bazaar, an area with many jewellery shops, also in the city's south. The third blast was at Dadar, in a street housing Muslim and Hindu shops in the centre of the coastal city. Chidambaram said 18 people had died in the attacks, lowering an earlier figure of 21.
– Cities across India are on high alert as security forces search for the culprits behind last night's deadly triple bombing in Mumbai that killed 17 people. No group has claimed responsibility for the attacks, which injured scores of people, the BBC reports. "All groups that have capacity to carry out such terror attacks are suspect," India's internal security chief told reporters. "All angles will be investigated, all leads will be followed." The bombings, which hit south Mumbai's jewelry market area, were the deadliest assault on the city since a terrorist attack in 2008 killed 166 people. Police believe a homegrown Islamic terror group may have been behind yesterday's operation, sources tell Reuters, although the choice of targets has caused some newspapers to speculate that the attacks are linked to a dispute in Mumbai's criminal underworld. Hillary Clinton says she has no intention of canceling her planned trip to India next week.