'The most important story of my life'

My week

Tuesday

I wake up in a friend's apartment in the east village of Manhattan. I happened to be in town the night before and stayed over as my home is in Connecticut. I wake in good spirits as there doesn't appear to be any urgent news in New York to deal with today, which means that I can write up an interview I've done with Helen Mirren.

At 8.55am I'm walking towards The Independent's office in midtown Manhattan – about six miles from the Twin Towers – when my cell phone goes. It's the news desk saying that a small aircraft has crashed into one of the World Trade Centre's towers, and would I mind diverting and taking a look because it might be interesting. I look south and can see thick smoke in the distance.

I get on the subway which moves more and more slowly the nearer we get to downtown. We get to City Hall and they start making announcements about a security incident at the World Trade Centre. The train won't go any further and I get out. I look up and both towers are burning. I'm shocked because I can't understand why both are on fire. I ask somebody what's happened, and he says two commercial jetliners have crashed into the World Trade Centre, one after the other. I think he's a crazy person because that doesn't happen, but everyone is saying the same thing.

On the one hand, I'm just simply mesmerised by the sight of the buildings burning, and on the other, I'm trying to understand what's happened. We quickly come to the conclusion that a terrorist attack has occurred. I'm less than half a mile away from the towers, and the police are trying to push the crowd back. People are pouring out of the financial district, but I'm feeling that as a journalist I should be pushing the other way to get a better sense of what's going on. I have my New York City Police press pass around my neck which entitles reporters to cross police lines. I get closer, and policemen start arguing with me. They're talking about the possibility of explosions. I have conflicting instincts: do I, as a reporter, go on further? Or do I do as I'm told and be sensible?

I didn't push any further forward, thankfully. I watch for a bit, feeling a combination of fascination and rapidly deepening anxiety. Fascination gives way to rank repulsion and terror when I begin to notice human beings jumping from very, very high floors like stunt men in a movie falling through the sky kicking. It's a truly horrifying sight that makes me want to throw up, and I start to cry. At this point it's no longer an extraordinary spectacle, but something that is utterly nightmarish.

As a reporter, I'm beginning to fret a little about deadlines and getting back to the office six miles away to write it all up. It's complete bedlam. I'm looking one more time and notice the corner of the south tower begin to bulge and buckle. I can't believe my eyes. The top quarter is beginning to break off, seemingly in slow motion. Then the bottom three-quarters just kind of melt, then the whole thing comes down on itself. It's just a stunning sight.

A lot of people start to weep spontaneously – everyone realises that they have just witnessed an awful lot of people dying. I weep, too. Then we see this huge wall of white smoke coming towards us at enormous speed. The police just start screaming at us to run. We start running for our lives: as far as we know, we don't know what this monstrous cloud contains.

Eventually, I see a taxi with a businessman in it going north. He's on his way to tell his children at school that he's all right as no one's cell phone is working. At this point, my family and friends are going nuts because I'm incommunicado. He lets me ride with him and I get to the office at about 11am, and ring the paper which expresses huge relief that I'm OK.

I then start to write. In a way it isn't difficult because what I've seen is so extraordinary it spills out of me. But I have huge difficulty when I get to the bit about people jumping out of the windows partly because I'm so upset by it, and partly because I don't quite know whether the readers can take it, it's so graphically awful.

Part of me is thanking my lucky stars I wasn't at the dentist this morning. As a correspondent here it would have been awful to have been out of town for what is becoming clearly the biggest news story of my life.

Wednesday

I get to bed at 2am at my friend's place. Two hours later, the newspaper wakes me with a request to watch the sun rising over the devastation. I walk towards the World Trade Centre. Part of the reason for setting off so early is to be under the cover of darkness, so I'm less likely to be stopped, even though I have press credentials.

The area is sealed off and I find myself in the midst of a huge rescue operation. I get close enough to see the stump of the building, which is a horrifying sight.

After dawn I'm corralled into a pen with all the journalists who have got that far. I watch as the army, the firemen, the doctors, the police and the sniffer dogs move into the area in carefully choreographed waves, while others are coming out exhausted having worked all night.

At 9am, I'm escorted with about 20 other journalists into the site where the towers once stood, now known as ground zero. We spend 10 minutes on a street corner just staring at it, and watching the rescue efforts. Then we're marched out and told to leave the area entirely.

I go back to the office, again under huge time pressure, to write another eyewitness piece, plus other news stories about the rescue. It's a very intense morning of work. The paper then says I must go home and rest because it's going to go on for days. In the meantime, I've been getting streams of phone calls and e-mails from family, friends and colleagues, enquiring after my welfare and that of my friends and family. It rather touches me. I take the afternoon off. I go out with some friends and have dinner. I'm in bed at 10pm. It's quite hard to make yourself go to bed because the TV stations are showing non-stop news, but I force myself and I sleep reasonably well at my friend's place.

Thursday

I get up at 7am and my assignment is to go to the two areas where friends and relations of missing people have collected, and I do interviews with them. They're all carrying these fliers with pictures and personal details of people who are missing. This is a very, very moving and emotional morning because these people are distraught, and they are crying on your shoulders as a reporter. It's very, very upsetting doing the interviews. I cry again. Earlier this year, I lost two family members, so I suppose in a sense I was more alive to their pain, as it reawakened my own in a way. All week, I find it very hard to remain collected and professional myself.

I rush back to the office at about 11am, again with a huge piece to write about that, plus other news pieces. So it's another intense morning of work.

In the afternoon, I have to start preparing for another piece for Saturday's paper, profiling one of those people (see cover story). I need to find someone who has a missing relation who is a quintessential New Yorker. So I go down to the New York armory, an area that the city has set aside for relations and friends of missing people to collect, to register and give personal details of those people and to accept grief counselling if they want it.

I spend the afternoon and some of the evening looking for people and I find the son-in-law of a woman called Barbra Walsh. I go out with friends for dinner after that, and go back to my friend's place and watch TV. There are very distressing stories from some of the news networks that maybe some more terrorist cells have been arrested at all three New York airports, and the indication is that they have been planning another wave of attacks. It's very unsettling because you realise that maybe we are not out of danger in New York.

Friday

At about 1am when I'm asleep there's a huge thunderstorm, which opens with an enormous crack of thunder outside the window, and I wake up in utter terror because I think I'm listening to another building going down. I don't sleep very much after that because I'm upset. All the images of the previous few days don't leave, especially when you go to sleep.

I have to get up at about 6am because I have to write the piece about Barbra Walsh, so I stay in my friend's house with my laptop and start writing.

President Bush is coming so I have to find out where he will be and what time he's coming. We don't know because there's very intense security. My day ends reporting on his visit to New York.

I haven't had much reinforcement from the paper in terms of other reporters, because of the impossibility of transporting people here from London. However, this afternoon one of my colleagues is finally due to arrive.

It's been the week in which the city that I love has been transformed from a place of real optimism and colour, to a place that is afraid, nervous and for many people a place of very, very intense grief. And that's tremendously sickening and sad.

But it has also been a week when professionally speaking it has been astonishing. I don't imagine I will ever have a news story as important or as overwhelmingly shocking as this one. In a sense, I am fighting that contradiction that many journalists face sometimes where their best hours professionally are sometimes the worst hours for humanity.

David Usborne is New York correspondent of 'The Independent'