9/11 TEN YEARS ON: The Day the Twin Towers came down

Wreckage and burning debris plunged down and left the 110-storey structure critically weakened. Scores of people were trapped above the impact after the Boeing 767 ploughed into the core of the building between floors 93 and 99. Some office workers, and the passengers and crew aboard the aircraft, were already dead. Those trapped fled upwards in the hope of rescue but others, cut off from safety by the flames, leapt to their deaths.

Then, at 9.03am local time, the world recoiled in sickening horror as a second airliner was deliberately flown into the South Tower.

Everyone who saw it understood that America, and the West, were under attack.

The images of that day will last forever; some of them still too horrific to fully take in.

They range from the live TV footage as the second jetliner ploughed mercilessly into the second of the towers through to the flicker on President George Bush's face when an aide whispered news of the attacks in his ear as he sat with a group of schoolchildren in Florida.

And then there were the pictures of those fleeing the collapsing towers; anguished scenes of rescue from brave New York police and firefighters; confusion, courage and chaos on the streets of New York... and then unbridled fury against those who perpetrated the atrocities.

As the Eastern Daily Press reported the following day: 'In the blood-stained history of terrorism, there has never been a day as horrifying as September 11, 2001.'

Yet for most heading to work in New York and elsewhere across America, the start of the day was like any other; a clear blue September morning as commuters hurried to offices, boarded flights across North America, or tourists enjoyed the attractions the Big Apple has to offer.

But within moments of the start of the working day, events began to unfurl that would leave anyone alive in no doubt that September 11, 2001 was a day that would change the world.

Four jetliners would be hijacked, three crashed into landmark US buildings and a fourth downed in the Pennsylvania countryside as courageous passengers overpowered the terrorists.

Earlier, terrorists Mohamed Atta and Abdulaziz al-Omari had boarded American Airlines Flight 11 at Boston's Logan airport bound for Los Angeles with three other hijackers. It took off 14 minutes late at 7.59am.

Fourteen minutes later, United Airlines Flight 175, also bound for Los Angeles, left Logan with a further five hijackers aboard.

By 8.20am, American Airlines Flight 77 was airborne, heading from Washington Dulles International Airport for Los Angeles with five hijackers among its passenger list, while at 8.42am United Airlines Flight 93 left Newark International Airport bound for San Francisco with 37 passengers (including four hijackers) and seven crew members aboard.

The hijacking of Flight 11 was confirmed when a radio threat was heard from the cockpit and the aircraft deviated from its flight plan, turning 100 degrees south towards New York. Hijackers armed with small knives, who had earlier evaded airport security, had forced their way into the cockpit and taken over the aircraft. Two F-15 fighters were scrambled to intercept but because Flight 11's transponder was switched off, they were unable to track their target.

One of the flight attendants, Amy Sweeney, made a tearful call from the hijacked aircraft to Michael Woodward at the American Airlines Flight Services Office in Boston.

'We are flying very, very low. We are flying way too low,' and then her call ended abruptly amid a sickening crackle of static as Flight 11 crashed into the north face of the North Tower of the World Trade Center at 8.46am travelling at about 466 mph.

News breaks, initially of a small aircraft hitting the tower, had attracted film crews to the scene. President Bush was informed.

Meanwhile, in the air, Flight 77 was hijacked and its transponder turned off as passengers aboard Flight 175 made desperate phone calls to their loved ones before – at 9.03am – the second Boeing 767 crashed into the South Tower at 590mph.

This is the image that millions of people saw as news crews filming the first impact, captured the second live on TV with hundreds of police, fire fighters and rescue workers already at the scene or heading to the Twin Towers.

In Florida, President Bush was about to begin reading The Pet Goat to the students when his Chief of Staff Andrew Card whispered in his ear: 'A second plane hit the second tower. America is under attack.'

It is something much of the world already knew; the image of so many people dying live on TV as the second aircraft ploughed into the World Trade Center is one that will haunt a generation.

Bush momentarily flinched, regained his composure and continued with the lesson as the fourth hijacked aircraft, Flight 93, changed direction over Ohio.

And then, some 30 minutes later, Flight 77 crashed into the western side of the Pentagon killing all aboard and 125 people on the ground.

Soon after that, US airspace was shut down to all civilian aircraft. Despite this, the military were unable to locate the hijacked aircraft and it was left to the courage of the passengers on Flight 93 to take their own action and attempt to overpower the hijackers.

Across Lower Manhattan, smoke billowed horizontally across the skyline with the Statue of Liberty defiant in the foreground but the unimaginable happens – again live on TV – and the South Tower of the World Trade Center collapses at 9.59am, claiming the lives of trapped office workers and scores of police, firefighters and rescue workers.

Three minutes later, Flight 93 is brought down south east of Pittsburgh, in Pennsylvania, and at 10.28am, the North Tower of the WTC collapsed. America and the world were aghast and in no doubt that they have been attacked in the most audacious and complex terrorist attack ever.

With many aircraft still in the air – and military jets under orders to shoot down any plane they could verify as being hijacked – the world held its breath, uncertain where the next target would be.

As fires raged at the Pentagon and rescue operations swung into effect in New York, American forces globally were put on high alert as the thoughts focused on casualties.

At a mid-afternoon press conference, New York Mayor Rudy Giuliani was asked to estimate the number of casualties at the World Trade Center. 'More than any of us can bear,' he replied.

The full casualty list would not be known for days. But it later emerged that a total of 2,977 people died in the 9/11 attacks, their names recited annually on the anniversary.

Among the 2,753 victims who died in the attacks on the World Trade Center were 343 firefighters and 60 police officers from New York City and the Port Authority, and eight private emergency medical technicians and paramedics. Another 184 people were killed in the attack on the Pentagon and all those on Flight 93 were killed. Most of the casualties were civilians, including nationals of over 70 countries. Among them were 67 Britons. The 19 hijackers also died.

But while many of the thousands who worked at the World Trade Center did escape with their lives, many were injured or mentally scarred by their experience.

Having flown back to the White House on Air Force One, President Bush addressed the nation at 8.30pm. He told America and the world: 'terrorist attacks can shake the foundations of our biggest buildings, but they cannot touch the foundation of America.'

He continued: 'The search is under way for those who are behind these evil acts… We will make no distinction between the terrorists who committed these acts and those who harbour them.'

The TV images showed the shock and disbelief on the faces of New Yorkers as they watched the World Trade Center burn and then, one after the other, the two symbols of American financial might tumble in a deadly and choking cloud of debris and dust.

But America and the world knew that the only superpower on earth had been caught with its guard down by a group of fanatical terrorists armed with little more than craft knives. Its airport security procedures were exposed as tragically flawed.

In the days that followed the shock and sorrow would turn to revenge.

Simultaneously, stories emerged of the victims, of those trapped making one final call to loved ones, tales of tragedy such as that of a survivor who found his sister died on the Boeing 767 to hit the second tower.

Only one tower was insured as the chances of both collapsing at the same time was considered too far fetched

There was silence, sorrow and anger at the two US air bases in the region – Mildenhall and Lakenheath – where security was stepped up as the US personnel shifted towards a war footing to avenge the attacks with America sure it was the work of Osama bin Laden.

Shattered images of the site – now known as Ground Zero – were constant.

Meanwhile, as the days passed, New York aimed to return to normality.

Three minutes silence in memory of victims was held on Friday, September 14, 2001 and East Anglia paused along with much of the world.

But as that day – September 11, 2001 and now known simply as 9/11 – came to a close, President Bush opened his journal and wrote: 'The Pearl Harbor of the 21st century took place today.'

Monday: The military response to 9/11