KEY POINTS:
The killers came by sea. They launched dinghies from a larger boat and under the cover of night slunk ashore, loaded up with munitions.
They docked near the Gateway of India monument, a landmark basalt arch where sea travellers from bygone eras would have first set eyes on amazing Mumbai, once called Bombay.
Groups of fair-skinned and foreign looking men - as described by witnesses - did not have far to go.
Their targets - hotels and venues used by Westerners, a Jewish centre and the city's biggest and most elaborate railway station - were just a short walk or a short highjacked car-ride away.
The men split into groups and got to work on their carefully-planned and stunningly co-ordinated carnage.
On the way to their targets they fired at random people and lobbed grenades and the teeming city of 18 million people descended into panic and chaos.
India's crack commandos, called the Black Cats, waged room to room battles in the hotels, freeing guests trapped in their rooms and killing some of the suspects.
Late yesterday, the Indian army had taken control of the Oberoi Hotel, freeing 30 hostages and freed most hostages from the Taj Mahal Palace Hotel's new building. A raid had commenced to free hostages still trapped in the Chabad Lubavitch Jewish centre.
As Indian forces battled to regain control, debate turned to who the killers were, and what were their aims.
Around nine of the gunmen are said to have been killed by police and commandos - but some were captured alive.
One prisoner was said to be Pakistani and the Hindu Times reported that three were said to have confessed to belonging to Lashkar-e-Toiba, one of the biggest Islamic militant groups in South Asia. Based in Pakistan, their name means Army of God.
Lashkar had earlier denied any role.
Interrogators of the prisoners said one or more groups of Lashkar operatives left Karachi in a merchant ship early on Wednesday, then launched their small boats.
Bharat Tamore, an assistant supervisor at the Taj Mahal Hotel, was on his way to work and told the Times of India that as he went past the jetty he noticed an unusual inflatable raft among the fishing boats.
"In the darkness, I saw eight young men stepping out of the raft, two at a time. They jumped into the waters and picked up a haversack. They bent down again and came up carrying two more haversacks, one in each hand."
They were in their 20s and fair-skinned, and they melted away into the darkness, he said.
Tamore carried on to work only to be caught up in the gunfire at the Taj, where he says he recognised the men from the jetty.
As people struggled to understand the attacks, India's Home Minister, Shivraj Patil, told Cabinet he believed the terrorists were targeting the top brass from the Mumbai Anti-Terror Squad.
The strategy was to get ATS chief Hemand Karkare to either of the terror targets and eliminate him there.
Karkare was killed, apparently amid a mix of gunfire and grenade blasts, within hours of the onset of the terrorists operation. His crackdown on India's militant groups had sparked warnings months ago of dire consequences. Fifteen more security personnel were also killed, along with around 120 other people.
More than 320 people were injured - 294 civilians, 26 policemen and 7 foreigners - but the carnage could have been much worse. CNN reported authorities had found eight kilograms of RDX, "one of the most powerful kinds of military explosives" at a restaurant not far from the hotel.
While the attacks were under way, a sea and air search was launched by India to find the terrorists' "mother ship".
A joint operation between the Navy, Coast Guard and the Border Security Force reportedly apprehended two Pakistani cargo ships suspected of ferrying the attackers to the coast. The ships - MV Alpha and MV Al Kabir - were on their way to Karachi.
India's three sea-guarding forces had been on routine joint exercises off the Gujarat coast when they received intelligence and immediately diverted.
While India was anxious for the attacks to have been planned over the border in Pakistan, responsibility may reflect terrorism's growing internationalism.
Spy agencies around the world were caught off guard by the deadly attack, in which gunmen sprayed crowds with bullets, torched landmark hotels and took dozens of hostages.
The attack illustrated just how fluid terror tactics have become since September 11 - and how the threat has become more global. Al-Qaeda's leaders on the Afghanistan-Pakistan border still provide inspiration but groups are becoming increasingly local.
Global intelligence sources say though the attacks bear the trademarks of al Qaeda - in that they were simultaneous and the targets were Westerners - the clues point to Indian terrorists.
One theory is the aim was to ruin peace talks between India and Pakistan, both of which are nuclear-armed, because the new Government in Pakistan is showing signs of genuinely wanting peace. The attacks threaten to chill improving ties between the rivals just as the West is trying to get Islamabad to focus on al-Qaeda and Taleban close to the Afghan border with Pakistan.
Though India's Deccan Mujahideen claimed responsibility for the attacks, intelligence agencies believe the operation was planned and executed by Lashkar-e-Toiba.
One of the suspects is said to have called an Indian television station speaking Urdu, the main language of Pakistan.
The man demanded the return of Muslim lands and is assumed to have been referring to Kashmir, a territory claimed by both India and Pakistan.
Ajai Sahni, head of the New Delhi-based Institute for Conflict Management, who has close ties to India's police and intelligence, says the attacks are a departure from past assaults waged over Kashmir, in that previous attacks have targeted Indian legislators, not Westerners.
A British security official told the Associated Press the attack did not look to have been directed by al Qaeda's leadership, which has been weakened by the deaths of several leaders in recent months.
Al Qaeda's core leadership is believed to be fewer than 100 people now, said Rohan Gunaratna, author of Inside Al-Qaida and a terrorism expert at the International Centre for Political Violence and Terrorism Research in Singapore. He said the attack was inspired by Islamic extremist ideology and al Qaeda propaganda popular among radicalised youths. Many of the attackers in Mumbai were young.
While earlier generations of terrorists were mostly linked to Pakistan, things have changed dramatically, he says.
"They are almost all homegrown groups.They are very angry and firmly believe that India is killing Muslims and attacking Islam."
Indian Prime Minister Manmohan Singh blamed "external forces" but stopped short of blaming Pakistan.
In September, a massive suicide truck bomb devastated the Marriott Hotel in the Pakistani capital, Islamabad, killing at least 54 people, including three Americans and the Czech ambassador.
"This type of terrorism is spreading, through Pakistan and now India, but we were all surprised by such a large-scale attack like this," said Wajid Hassan, Pakistan's High Commissioner in London.
"This is no coincidence that this type of attack happened so soon after the bombing of the Marriott Hotel. People from all countries are being paid to fight this al Qaeda war. This is a war that goes beyond any nationality."
The BBC's security correspondent, Gordon Corera, reports that India and Mumbai, are no stranger to terrorism but the attacks on multiple targets in the city mark a significant change.
Previous attacks involved the leaving of explosives in public places like markets or trains, and these could be devastating in terms of loss of life - nearly 200 people were killed this way in 2006. "But the latest attacks are different in terms of both method and scale," he writes.
"With teams of well-armed men involved in synchronised attacks, the gunmen were also clearly prepared to die in their attacks."
Another major difference is the targeting of restaurants and hotels used by Westerners and the apparent singling out of those with British and American passports.
United States President-elect Barack Obama has said he wants Pakistan to refocus its attention on the threat from al Qaeda and the Taleban on its western border rather than Kashmir and India to the East, but there is little sign that the Pakistani military is ready to do that.
Shah Mehmood Qureshi, Pakistan's Foreign Minister who was in India for peace talks, urged Indians not to "jump to conclusions."
Lashkar-e-Toiba also has connections al Qaeda and the Taleban, and the attacks on Western targets, and particularly the attempts by the militants to single out hotel guests with British and American passports, have encouraged the suggestion here may have been al Qaeda involvement. The group has also been associated with India's domestic Islamic terrorists, who have used the name the Indian Mujahideen since 2007, an offshoot of the Students' Islamic Movement of India.
They were blamed for the explosions on commuter trains in Mumbai two years ago which killed 187 people and warned in an email in September: "Let the Indian Mujahideen warn all the people of Mumbai that whatever deadly attacks Mumbaikars will face in future, their responsibility would lie with the Mumbai ATS [anti-terrorist squad] and their guardians."
In May the organisation, headed by Abdul Subhan Qureshi - known as "India's bin Laden" - threatened to attack tourist sites unless the Indian Government withdrew its support for America. It has claimed responsibility for bombings in Bangalore, Ahmedebad and Delhi since July.
Whoever carried out the attacks, their demands so far have been vague.
A militant inside the Oberoi Hotel told Indian television by telephone: "Release all mujahideens and Muslims living in India should not be troubled."
The caller to the television station, who called himself Imran, said: "Ask the Government to talk to us and we will release the hostages. Are you aware how many people have been killed in Kashmir?
"Are you aware how your army has killed Muslims?"
Early warnings:
Not only did India's Deccan Mujahideen claim responsibility, for the attacks, but back in September media outlets were warned by a group called the Indian Mujahideen of possible mayhem in Mumbai. The Indian Mujahideen has claimed responsibility for attacks in Delhi, Ahmedabad, Bangalore and Jaipur. In recent months, hundreds of people have died. The Indian Mujahideen accuse the police of harrassing young Muslims.
In an email to media, addressing the police they said: "You should know that your acts are not at all left unnoticed; we are closely keeping an eye on you and just waiting for the right time to execute your bloodshed. We are aware of your recent raids at Ansarnagar, Mograpada, and the harassment and trouble you created there for the Muslims.
"You threatened to murder them ... you even dared to abuse and insult Maulana Mahmood-ul-Hasan Qasmi and even misbehaved with the Muslim women and children there.
"If this is the degree your arrogance has reached, and if you think that by these stunts you can scare us, then let the Indian Mujahideen warn all the people of Mumbai that whatever deadly attacks Mumbaikars will face in future, their responsibility would lie with the Mumbai ATS and their guardians."
Suspicion falls on Pakistan militant:
Analysts said the tactics used in Mumbai appeared to be inspired by those of al Qaeda or groups linked to al Qaeda, such as the Pakistan-based Lashkar-e-Toiba.
Lashkar, which was blamed for the 2001 attack on India's Parliament that brought the nuclear-armed neighbours close to war, is fighting Indian rule in revolt-hit Indian Kashmir.
LeT has recently emphasised the idea of waging jihad against India, rather than just liberating Kashmir. It has also shared training camps in Afghanistan with al Qaeda, and LeT fighters were among the dead in US missile strikes on al Qaeda training camps in Khost, Afghanistan, in 1998.
Since it was banned by Pervez Musharraf, then President of Pakistan, in 2002, LeT has rarely claimed responsibility for any attack, fearing that this would bring further pressure on the Pakistani authorities to crack down on it. In several attacks attributed to the group, militants have left pamphlets or phoned the media using previously unheard-of names.
While planning for the attack probably took place in Pakistan, the plotters may have used a local group in Bombay to execute it. Suspicion has fallen on the Indian Mujahideen as that partner.
- AGENCIES
