September 11 will be forever engraved in the minds of the millions of people around the world who watched TV footage or witnessed first-hand the terrorist atrocities in America.

It was described in an official report into the events as "a day of unprecedented shock and suffering in the history of the United States."

On this day in 2001 almost 3,000 people were killed when Islamist extremists launched a series of co-ordinated attacks on the country and destroyed one of its famous landmarks.

Live news reports broadcast around the globe captured the moment the most powerful nation on earth was shaken to its core by a suicidal act that beggared belief.

At the height of New York’s morning rush hour, the first of four hijacked passenger jets on internal flights was deliberately flown into the north tower of the World Trade Center, sending a huge plume of black smoke into the city skyline.

Apart from the hundreds of people who died instantly in the impact, hundreds more were trapped inside the building as it turned into a towering inferno, including Neil Cudmore and his fiancée, Dinah Webster , and Simon Turner , who were all attending a conference near the top of the tower, and stockbroker Jeremy Carrington . They also perished.

Minutes later, with television cameras turned on the burning tower, disbelief turned to horror as the second airliner crashed into the south tower, creating a massive fireball.

Barely had a grim-faced President Bush declared a national tragedy than the third plane smashed into the Pentagon in Washington, the nerve centre of the US military.

The fourth plane crashed in a field in Pennsylvania after some of the passengers tried to overpower their captors when they realised America was under attack. The aircraft had been heading for the White House, or the United States Capitol in Washington.

An hour and a half after the terrorists had launched their audacious assault the World Trade Center in Lower Manhattan lay in ruins and a five-storey section of the Pentagon had collapsed.

Excluding the 19 Arab hijackers, more than 2,600 people lost their lives in the twin towers and on the ground in New York: 256 died on the four planes and 125 were killed at the Pentagon.

The death toll exceeded that caused by the Japanese attack on Pearl Harbor in 1941 which brought the Americans into the Second World War.

Most of the victims of 9/11 – as it has come to be known – were civilians and more than 90 countries lost citizens in the attacks on the World Trade Center, which with its 110 floors of office space had been a symbol of New York.

There were plenty of warnings in the years preceding the attacks that Muslim fanatics were intent on killing Americans indiscriminately and in large numbers.

In February 1993, a group led by Ramzi Yousef tried to destroy the World Trade Center with a truck bomb, killing six and wounding a thousand.

Five years later Usama Bin Ladin, a wealthy Saudi, and four others issued a fatwa, publicly declaring that it was God’s decree that every Muslim should try his utmost to kill any American, military or civilian, anywhere in the world, because of American "occupation" of Islam’s holy places and aggression against Muslims. He objected in particular to the presence of US troops in Saudi Arabia, the home of Islam’s holiest sites, and American policies in the Middle East.

Months later Bin Ladin’s group, al Qaeda, carried out near-simultaneous truck bomb attacks on the US embassies in Nairobi, Kenya, and Dar es Salaam, Tanzania, which left 224 people dead, including 12 Americans, and injured thousands more.

During the spring and summer of 2001, US intelligence agencies received a stream of warnings that al Qaeda planned, as one report put it, "something very, very, very big."

But despite Bin Ladin’s determination to strike in the United States, a fact that President Bush was reminded of during a briefing in August 2001, the specific threat pointed overseas and the attacks took the country by surprise.

America’s worst day had long-term repercussions, resulting in the war on terrorism which saw the United States and its allies, including Britain, drawn into conflicts in Iraq and Afghanistan in the fight to defeat al Qaeda and its supporters.

But there were many tales of heroism that emerged from the disaster. More than 400 firefighters, police officers and other rescue workers sacrificed their lives to try to help the survivors.

The commissioners, who drew up the 9/11 Commission Report, paid tribute to them, saying: "The civilians, firefighters, police officers, emergency medical technicians, and emergency management professionals exhibited steady determination and resolve under horrifying, overwhelming conditions on 9/11.

"Their actions saved lives and inspired a nation."