TELEVISION brought what was happening up close and terrifying. And what it looked like was the end of the world. Initially it was hard to see what was going on. First one plane had crashed into one of the twin towers of the World Trade Centre in New York. The TV talking heads, breathless with shock and the effort of running to wherever they were speaking from, speculated about whether this was an accident or a terrorist attack.

The stricken tower smoked furiously, a gargantuan smoke-stack sending black clouds into a clear blue sky. And then a plane crashed into the other tower, right there on television - a modern horror story, transmitted live as the news announcers were still grasping for an explanation.

In this office, and in others where the television is always on, keeping the world a touch of the handset away, people stopped what they were doing and crowded round the television, brought together by appalling news, a congregation at the altar of the unspeakable.

There is a sickening excitement at such moments, but the second-hand adrenaline surge soon fizzes out, leaving just the sickness, the appalled fascination, the needing to know and the wanting not to know.

What we watched was horribly real, and yet mostly the suffering was unseen, the human cost hidden in the smoke and the destruction. It was obscene, it made no sense but we watched.

As the two towers burned, another section of the television revealed the Pentagon in flames. The modern screen can accommodate any outrage: as the Pentagon burned in one corner, the clouds rose higher in Manhattan in the other.

While an American news anchorman spoke of an aircraft crashing into the Pentagon, one of the trade towers was about to go. This 110-storey monument to everything proud and American imploded, collapsing in on itself in a rising mountain of dust.

The television filled with images seemingly drawn from a scare-mongering Hollywood movie, one of the sort that specialises in showing America under threat.

And yet this was no paranoid fantasy. Blue-jacketed FBI officers scuttled in the restless dust. Reporters, microphones in hand, gazed skywards. With heads tilted, their stance seemed almost religious, as if they were looking at the oncoming apocalypse, which in a sense they were.

In the middle of this orchestrated terror, a personal memory came back. Lying on the Manhattan pavement, I point the Olympus Trip camera at the skies, attempting to capture the dizzying towers of the World Trade Centre. My good friend laughs but he is now dead, taken by a brain tumour; the towers glint in the August sun but they are now gone, reduced to twisted metal and a cruel catalogue of loss.

If terrorists can wreak such murderous havoc in New York, if they can desecrate the Manhattan skyline, if they can send hi-jacked planes crashing into the Pentagon, there is no dreadful, earth-stuttering atrocity that is not within their power. Are any of us safe anywhere?

And this is what remains so frightening about the worst act of terrorism anyone can remember. A few bad men, unhinged by fanaticism but certain of their cause, can make the world wobble on its axis.

Almost as scary as what has happened is what sort of vengeance President Bush will exact for this most appalling of acts.

As the smoke drifted and the dust settled, it was hard not to shudder at the suddenly very real thought that all-out world war might not just be the province of movie-makers feeding off their audience's primal fears.

This one might just be for real.