Crammed into a stairwell of the second tower of the World Trade Centre, surrounded by hundreds of panicking people, we were suddenly shaken by a massive explosion.

Some screamed, others were thrown down the stairs as the 110-storey building suddenly began to shake like a leaf.

That was when I thought my time was up. Poised precariously hundreds of metres up in the air, we had no idea what was happening and I honestly believed the building was about to collapse.

But I never gave up. I was determined to get out.

Just 40 minutes earlier, I had arrived at my desk working at the insurers AVO, on the 93rd floor of the twin towers.

I had only started this dream job four weeks previously and I had told my parents that this was the happiest I had ever been.

I moved to New York three years ago, after graduating from Sydney University law school. I had a close group of friends, both Australian and American, and my career was going perfectly.

At 8.42am I put down the phone after a conversation with a colleague in Atlanta. As I did so, I heard a huge explosion.

Right in my line of sight I saw four floors of the first tower explode. There was glass, flames, and I remember paper drifting through the sky like confetti.

I thought a bomb had gone off. I was doing 360-degree turns. My mind was just blown apart.

The public address system told us that the building was secure. I went back to my desk to stay and follow instructions, and started collecting all my stuff together to start work.

It was then that I just got a message in my head saying: "Get out of here."

If I'd delayed another two minutes, I wouldn't have survived.

I went to the nearest fire escape, which turned out to be diagonally opposite from where the plane eventually struck. Some of my colleagues followed, others didn't. I've no idea how long I'd been going down when the plane struck our building, but it felt very close.

I twisted my knee but I just kept going down the stairs. People were throwing off their shoes and leaving their bags behind, trying to get out.

It was terrible.

The camaraderie of everyone was great, people were helping each other along, encouraging each other.

I kept shouting to everyone that we were going to make it. I didn't believe it.

Climbing down 92 floors in business shoes, trousers and shirt with a lot of sweaty, panicking people is quite an ordeal.

When we got down to the forties, it just seemed like we were standing still.

Eventually, I got to the bottom, with four people on each arm.

Going in the opposite direction were the bravest and most wonderful people – firemen and police. They're probably all dead now.

I got outside and it was an absolute mess. There was devastation everywhere. I just kept going. A few minutes later, I heard the second tower come crashing down and saw the smoke start billowing.

Somehow I made it to a friend's in Greenwich. I rang my parents and just said: "Hi Mum, it's me." Then I started sobbing.

It's like I'm living in a nightmare now. There were 1600 people in my office; 1200 are missing. My office doesn't even exist. The girl I was dating, her father's still missing. I haven't dared call.

I've had friends from floors below me die. It's heartbreaking.

It's hard not to feel guilty. You think: "What if I'd done this, what I'd done that?" I just push those thoughts back. I was just one of the lucky ones.

I've hardly slept – the first night I just kept shaking.

Sometimes I feel furious, sometimes just a sense of loss.

There's a lot of feeling of resentment against the people who did it.