Over the past 20 years, Mumbai has suffered vicious communal riots, repeated bomb attacks, persistent gang violence, and political assassinations.
It is India's most prosperous city, its most outward-looking - and also its most volatile.
Still, the scale and sophistication of these audacious attacks will be shocking for the 20 million people who live in and around Mumbai - and for a country whose growing prosperity is in large part built on the city's commercial success.
The targets included the main rail station, one of the world's busiest, and the sort of hotels and restaurants patronised by local and visiting business leaders.
The country has been captivated and horrified by live television pictures of flames leaping from the roof of one of its grandest hotels - and of troops surrounding another Mumbai luxury hotel to root out remaining assailants.
India's TV news channels have, in the initial hours of the drama, largely refrained from pointing the finger of blame.
The claim from a little-heard-of organisation, Deccan Mujahideen, may harden suspicions that Islamic radicals are involved.
Two years ago the authorities blamed a series of bomb attacks on Mumbai commuter trains on Islamic militant groups once based in Pakistan.
Back in 1993, a string of co-ordinated attacks on landmarks across Mumbai, bombings which left hundreds dead, were widely believed to have been the work of organised crime.
The Indian authorities held neighbouring Pakistan responsible for organising those bombings, an allegation angrily rejected in Islamabad.
But there are other possible culprits.
Some recent bomb attacks - though on nothing like this scale - have been blamed on militant Hindu organisations.
The motive is far from clear. The choice of targets might suggest an attempt to undermine business confidence and put off foreign investors.
Some may wonder whether the attacks are intended to frustrate attempts to improve relations between India and Pakistan.
Or perhaps they are designed to destabilise the world's largest democracy.
A nationwide election is expected in the next few months, and there are regional elections currently being held in several Indian states.
One is in Indian-administered Kashmir, the Himalayan region whose disputed status has been the main cause of 60 years of tension and conflict between South Asia's two nuclear neighbours.
Indian security forces have been exchanging fire with gunmen holding dozens of hostages in two luxury hotels in the Indian city of Mumbai (Bombay). Troops surrounded the premises shortly after armed men carried out a series of co-ordinated attacks across the city, killing 101 people and injuring 287.
The hotels were among several locations in the main tourist and business district targeted late on Wednesday.
Police say four suspected terrorists have been killed and nine arrested.
The situation is still volatile in two of the most high-profile targets of Wednesday's attacks - the Taj Mahal Palace and Oberoi Trident hotels, where armed men are believed to be holding about 40 hostages.
There are reports of intermittent exchange of fire between security forces and the armed attackers barricaded inside both hotels.
Correspondents say security personnel have so far not stormed the premises perhaps for fear of endangering the lives of hostages, some of whom could be Westerners.
Eyewitness reports suggest the attackers singled out British and American passport holders.
If the reports are true, our security correspondent Frank Gardner says it implies an Islamist motive - attacks inspired or co-ordinated by al-Qaeda.
A claim of responsibility has been made by a previously unknown group calling itself the Deccan Mujahideen.
Our correspondent says it could be a hoax or assumed name for another group.
In other developments:
• Fire crews evacuated people from the upper floors of the Taj Mahal Palace, where a grenade attack caused a blaze
• Israel says it is concerned for the safety of its citizens in Mumbai, as a rabbi and his family are feared captured by gunmen
• The head of Mumbai's anti-terrorism unit and two other senior officers are among those killed, officials say
• The White House held a meeting of top intelligence and counter-terrorism officials, and pledges to help the Indian government
• India's Bombay Stock Exchange and National Stock Exchange markets are closed, as the authorities urge local people to stay at home
• There are unconfirmed reports that five gunmen have taken hostages in an office block in the financial district of Mumbai.
The city's main commuter train station, a hospital, and a restaurant popular with tourists were among at least seven locations caught up in the violence.
Local TV images showed blood-splattered streets, and bodies being taken into ambulances.
One eyewitness told the BBC he had seen a gunman opening fire in the Taj Mahal's lobby.
"We all moved through the lobby in the opposite direction and another gunman then appeared towards where we were moving and he started firing immediately in our direction."
One British tourist said she spent six hours barricaded in the Oberoi hotel.
"There were about 20 or 30 people in each room. The doors were locked very quickly, the lights turned off, and everybody just lay very still on the floor," she said.
There has been a wave of bombings in Indian cities in recent months which has left scores of people dead.
Most of the attacks have been blamed on Muslim militants, although police have also arrested suspected Hindu extremists.
The BBC's Sanjeev Srivastava says the timing and symbolism of the latest attacks could not have been worse.
By choosing to target the richest district of India's financial capital in such a brazen and effective manner, he says those behind the attacks have perhaps dealt the severest blow to date to the morale and self esteem of the Indian authorities.
The attacks have come amidst elections in several Indian states and exposes the governing coalition to the charge that it has failed to combat terror, our correspondent says.