The scene resembled a city at night, observed from a plane as it comes in to land: a map of winking lights, in tight and not-so-tight clusters, creating an involuntary pattern of its own. But this was a city seen on the ground, not from the sky. This was Mumbai, scarred and bloodied by terror attacks, its people coming out to mourn the dead in an overwhelming show of solidarity for the victims of 26 November.

Near the Gateway of India, on the edge of the Arabian Sea, thousands of candles lit up the gloaming on the evening of Wednesday 3 December.

India is no stranger to terror attacks and Mumbai is hardly new to catastrophe. Yet the scale and the intensity of this candlelit vigil were unprecedented in the history of contemporary India. No one in particular had organised it; there had been no official announcement. Word had spread by text message and the internet, and tens of thousands of people had turned up hours before 6pm, the scheduled start of the march.

In the event, there were as many as 50,000 people out on the streets, the most unlikely congregation of people to have marched in this city. People stood on the tops of cars and vans. They lit candles on the roads and the pavements, creating mini-shrines for the departed in the usually chaotic and frenzied southernmost tip of the Mumbai peninsula.

People were wearing T-shirts with slogans such as "I love Mumbai" and "Enough is enough". Every other person seemed to be wearing one, making the marchers on the move seem, from a distance, like a gently undulating sea of white. There were national flags so large that ten people were required to hold each one aloft. There were street plays. There were chants of "We want justice". There was anger directed at the ineptitude of politicians. This felt like the most concerted and urgent call for participatory democracy in recent times.

Above all, there was a sense of a devastated city, a city having found a way of showing emotions that had been building up for the past week.

Fear permeates life in Mumbai now. Security has been bolstered at schools, colleges, malls, cinemas, stadiums, airports and offices. But husbands still ask their wives to call every 15 minutes, and people become panicky when loved ones have been out of touch for longer than that.

People are staying together, and, given the choice, they are staying home more than ever before. Newspapers have reported how flight bookings have dropped for travel within India; how blockbuster Hindi movies are playing to nearly empty theatres on their opening weekends; how occupancy at hotels has declined; and how restaurants and bars that are usually packed have many tables empty on any given evening. Several luxury hotels have cancelled their New Year's Eve parties. Eid celebrations were muted.

Azam Amir Qasab, the lone terrorist who survived the murderous onslaught, and who is now under arrest, has spoken of how he and his nine partners were chosen, trained and directed. India says the evidence that the terrorists were from Pakistan is incontrovertible, and has asked its neighbour to hand over certain men they suspect are involved in masterminding the attacks. Pakistan, having already arrested a commander of the jihadist organisation Lashkar- e-Toiba, is under pressure to act - not least from the US (FBI officers are in Mumbai). Manmohan Singh, the prime minister, has talked of setting up a US-style federal investigative agency.

But the Indian people, weary of bluster and wary of rhetoric, are not ready to believe in promises until they see them fulfilled.

The attacks have done something else to Mumbai: they have altered its self-image. This is India's most triumphantly self-absorbed city. It is a city which thinks that being insular is not merely what it is, but a right that it has earned for itself. Yet the attacks are forcing Mumbai not only to look inward, but out to the political capital, Delhi, to see what help might be forthcoming. The people of Mumbai are also looking to other cities in the world to find out how they have dealt with extreme terror attacks.

Has something definitively changed about Mumbai? Or are we witnessing merely a response to terrible events that the city has not yet come to terms with? As it has been little more than a fortnight, it is still too soon to tell.

Soumya Bhattacharya is the editor of the Hindustan Times in Mumbai and author of the memoir "You Must Like Cricket?", published by Yellow Jersey Press (£12)