There was rubble in the street, there were cars on fire, and the entire air was littered with burning paper

It’s September 11, 2001. This is Hans Kunnen’s eyewitness account after surviving the al Qaeda attack on the Twin Towers in New York’s financial district.

‘I started the day at a breakfast meeting of economists at the World Trade Center Marriott Hotel, which sits right between the Twin Towers, ground floor.

‘We were listening to a speaker from Morgan Stanley, and all of a sudden, the room shook. The table shook, the chandelier shook. It felt a bit like, you know, an earthquake. I thought it was maybe an explosion of a generator. But people just up and left.

‘People were coming in from outside and with one particular lady, she was singed. She’d been burned. And she was crying and screaming and people ran to help her and others. They’d come inside because debris had fallen down the side of the towers.

‘There was no panic, or huge, you know, pandemonium at that stage. But the folk said, ‘Look, you can’t go upstairs, alarm bells are ringing, you have to leave.’

‘And it was then that it became obvious that something really strange was happening. Because there was rubble in the street, there were cars on fire, and the entire air was littered with burning paper.

‘I left the hotel and went across the road and looked up. And that’s when I first saw the smoke billowing out of the North Tower.

‘I was sixty metres, maybe a hundred from the bottom of the building. Which in comparison to the height of the towers, was right underneath. It’s like the pyramids, they just overwhelm you with their size.

‘So I’m standing there, on my own. Just looking up and you see this evil black smoke pouring out the building and you think, What on earth happened?

‘Because we didn’t know it was a plane. But then as we’re standing there, I heard a plane coming. And it was low. And it was accelerating and it banked.

‘And the noise of the plane over your head, and then the explosion was just jaw-dropping. I’ll never forget it.

‘And that’s when pandemonium took hold. People actually saw it for themselves.

‘One thing that has stayed with me was the sight of a particular lady blown out of a window and she cartwheeled across my horizon, like a rag doll.

‘That was a sight I shall never forget and said, ‘Okay, Hans you really need to get out.’

‘You realize you in the bull’s eye of an attack. And there could be three, four, five, six more planes coming in the next minute. And it’s good not to be here.

‘I decided the best place for me was to catch a ferry across to Staten Island but like the Manly ferry - 800 meters, a kilometer I think it might be to the Staten Island Ferry Terminal.

‘And then sat inside the ferry terminal, waiting for a ferry. You could cut the air it was so tense with anger, fear, distrust.

‘I thought I’m gonna die because all of a sudden, the entire Ferry Terminal shook.’

Al Qaeda struck at the heart of the United States, taking down the twin towers in New York's financial centre, striking the Pentagon, and crashing another plane in Pennsylvania. Nearly 3,000 people were killed in the assaults, which catapulted the US and the West into a 20-year war in Afghanistan.