Amid the choking clouds of toxic dust sweeping through the streets of Manhattan as the Twin Towers of the World Trade Center crumpled, the haunting image that reappears for Greg Hayman is of the dumbstruck, dust-caked figures emerging from debris.

Too shocked to speak, the ghostly figures reached out for help.

Only moments earlier, those above them had leapt to their deaths as the ferocious fire and choking smoke engulfed the upper storeys of the World Trade Center towers.

Witnessing thousands of people die before his eyes as the towers collapsed is also a thought that Greg, now 53 and the mayor of Cromer, still struggles with as he tries to push it to the back of his mind.

Sometimes, it is not that easy – particularly as those images and memories are revived on the 10th anniversary of the atrocities.

A decade ago, Greg was in New York as head of communications for the British Library with two colleagues, preparing for the opening of an exhibition marking the centenary of the death of Oscar Wilde, which was transferring from the London establishment to the Morgan Library in Manhattan.

Having arrived in the city a few days earlier, he was awoken on the morning of September 11 in his room at the New Yorker hotel, near the Empire State Building, by a colleague who had been told of news reports of a plane hitting one of the Twin Towers.

'I turned on the news and then looked out of my window,' said Greg. 'I could see smoke rising from around one of the towers. My immediate thought was that there had been a terrible accident. It also crossed my mind that one of the things we had been thinking about doing that day was to go to the top of the World Trade Center.

'It was while I was watching the news in the room that I saw the second plane fly into the other tower on TV and that's when I knew something was terribly amiss and that this was no accident, that it was a terrorist attack.'

Worried that they were in a high rise hotel and at risk, they decided to go down to street level with a plan to make their way towards the lower rise buildings in Greenwich Village.

But at street level, they were left aghast by the scenes that greeted them.

'The World Trade Center was only four blocks away and we could see the shapes of people throwing themselves out – we had a clear view,' he recalled.

'The traffic all around us suddenly screeched to a halt as people stood in total disbelief as the first tower came down. It was a terrible experience.

'Seeing people effectively dying in front of us was overwhelming as there were obviously thousands of people still in there… and then the second tower fell.'

The choking dust cloud thrown up by the debris of the collapsing towers engulfed the area and people fled away in panic. Slowly, Greg and his colleague saw the ghostly figures emerge from the clouds of dust.

'Soon, the first walking wounded started staggering out of the dust like grey spectres. They were totally covered from head to foot in the foul dust from the collapsing buildings, covered everywhere except from where they were bleeding.

'We took them into caf�s and sat them down and helped to get them cleaned up and give them hot, sweet drinks. They were in a terrible state; shocked and monosyllabic.'

The lack of information on the street left people uncertain, paranoid and absolutely terrified with rumours of further attacks spreading rapidly as people began leaving New York on foot.

'They looked like an army of ants crossing the bridges to get out of Manhattan. We started walking but did not know where to go; we had nowhere to go,' he added.

'So, we went back to our hotel but the staff had started leaving. New York was falling apart by the afternoon, the whole infrastructure had gone.'

Shops, caf�s and restaurants were shutting down as all around them people tried to contact family members but that was difficult as mobile communication networks had stopped working.

'New York was in a state of shock and sheer terror, parts of the city ceased to function. The nearest I imagined it to be was of how London was in the Blitz but whereas London kept going, parts of New York didn't. New York literally stopped.

'One of the most moving things was the small shrines and candles that started appearing and the posters put up by people searching for loved ones,' said Greg. 'I still have one of those posters.'

For several days afterwards, Greg and his colleagues found themselves stranded at their hotel but food was running out and although no new guests were arriving as flights were grounded, everybody around him was trying to work out how to get away from New York. It was a further 10 days before Greg was able to leave the city.

'Even then at the airports it was chaos. Security was increased and everyone was nervous about flying but there was no alternative. They just wanted to get home.'

The impact of those tragically momentous events of a decade ago have been lasting for Greg.

'I hardly fly at all now,' said Greg, who was also working in London close to Aldgate East when the 7/7 tube and bus bombings happened in 2005.

But he added: 'What is really hard, and it is something I try to put to the back of my mind, is seeing all of those people dying when the towers collapsed. It is not something you get over.'

In the years since, Greg has worked as head of communications at Cambridge University but now –alongside his political career in Cromer as mayor – he is also seeking a new direction in life and pursuing his interest in art by studying at Norwich University College of the Arts.

He added: 'Experiences like this can be life changing; you realise how precious life is and you do not want to waste any time.'