Often described as the worst terrorist attack in history, the trauma of 9/11 is still felt keenly by many 20 years on.
Images showing the horrifying events unfolding – as first one and then a second hijacked plane hit the World Trade Centre, another struck the Pentagon and a fourth crash-landed in a Pennsylvania field – have lost none of their impact over time.
Perhaps those showing the human cost of the day, in which almost 3,000 died, are more poignant still – the fear on the faces of those fleeing for their lives, the exhaustion of the rescue workers battling to save whoever they could and the despair of those searching for missing loved ones.
And, later, people saw images of hope as crowds gathered for vigils, debris was cleared and people attempted to rebuild their lives and the city around them.
These pictures, viewed by millions around the globe in the aftermath of the attacks, led many to realise it had been a day that would change the course of history, not just for Americans, but for the world.
People inside both the North and South towers of the World Trade Center hung on for dear life after the planes hit on 11 September.
According to New York Magazine, 2016 people died who worked in the two buildings.
George W Bush, then president, was famously reading a storybook to a class of elementary students as he was informed about the attack.
He famously waited seven minutes for the book reading to finish before getting up, and later said he didn’t react so as not to scare the children. “I made the decision not to jump up ... and leave the classroom ... I didn’t want to rattle the kids. I wanted to project a sense of calm,” he said in a National Geographic Channel documentary.
The World Trade Center’s South Tower was hit approximately 19 minutes after the North Tower was hit.
Once the second tower was hit, there was no doubt that it was an attack. President Bush vowed to “find those folks who committed this act” while at the Sarasota primary school.
Passersby were forced to flee the scene in a panic as debris from the attack fell onto the street below.
Fires were ignited after the jet fuel interacted with other elements from the crash. After approximately an hour of burning, the buildings began to collapse into downtown Manhattan.
Most of the captured footage of the planes colliding into the New York City landmark were of the second plane. The first crash being such a shock, no cameras were pointing at it.
Mr Bush was told by an aide: “A second plane has hit the second tower. America is under attack”, during his book reading.
Residents and tourists of the city had no clue where it was safe to take refugee as they ran from the tumbles of smoke, fire and building parts flying towards them.
People in the immediate vicinity of the building were covered in ash caused by the crash.
The last survivor was pulled from the rubble of the collapsed buildings 27 hours after they fell. On later days, there were no people found alive.
New York City was not the only place impacted by the hijacked planes as the Pentagon was also a target for al-Qaeda. They hit the government building at 9.37am.
Half an hour after the first tower fell, the second began to crumble, leaving a path of destruction in its wake.
Clouds of smoke dominated as people tried to flee for their lives, begin the rescue mission and process what had just happened.
People were seen panicking after the towers fell as there had been reports of other planes. There was uncertainty about whether there was going to be another to hit the city.
Gerard McGibbon died earlier this year, aged 61. According to his obituary, he had three children with his wife Diana and was described as “the ultimate family man” who had managed to stay sober for seven years.
McGibbon was also a “dedicated” firefighter in New York City. In addition to helping after 9/11, he helped after Hurricane Sandy in 2012.
Marcy Borders worked as a bank teller at the Bank of America. After this picture emerged, she developed the nickname “Dust Lady” and gained international attention.
Borders carried significant trauma after 9/11. In 2014, she died aged 42 of stomach cancer she believed may have been a result of the dust and debris she was covered in on 9/11.
After the attack was confirmed, ambulances were deployed to scene as soon as possible, according to documents published by City Hall.
A collection of professionals tasked with clearing up the surrounding areas of the World Trade Center, an American flag is seen hanging in distance.
Many people said that American culture changed drastically by 9/11 as it was a catalyst for many international and domestic developments.
Smoke was said to be seen all across the lower half of Manhattan
Mr Fine worked on the 79th floor on the North Tower.
Ten years after the attack, he was quoted as saying, “I had no idea the photo was being taken but it became an iconic image. One picture editor told me it symbolised the resilience of the American businessman.”
According to New York City Hall, 91,000 rescue and recovery personnel were needed to clear up the destruction left by the events on 11 September.
In addition, they also have a scheme to claim compensation for any health issues caused during their work.
Firefighters were integral to the clear up
Lorisa Taylor, the woman they are looking for, was later found dead in the wreckage. According to her obituary, she had spent the previous evening celebrating her seventh wedding anniversary with her husband Frank.
She was 31, had three children and worked in insurance at Marsh and McLennan.
According to New York Magazine, 1.8 million tons of debris were removed from the scene in the nine months it took to clear the wreckage.
The Winter Garden, a shopping centre sustained a considerable amount of damage. However it also provided an escape route for many fleeing the building as it toppled, according to reports in 2002 by The New York Times.
It was first opened in 1988.
Out of the nearly 3,000 people that died in the attack, 412 were emergency workers, such as firefighters and police officers.
According to the Officer Down Memorial Page, 10 law enforcement agencies suffered losses.
Along with a plane hitting a wall of the Pentagon, a fourth plane crash landed in a field in Pennsylvania, it was said it was aiming for Capitol Hill, according to reports.
In the immediate period after the attack, it was unclear how many people were still missing.
According to NBC News, fifteen years after the attacks, some 40 per cent of people who were presumed dead had not had been identified yet, totalling 1,113 victims.
Some progress is believed to have been made as on 7 September, two more people were identified by local authorities, says reports.
St Paul’s Episcopal Church is found across the street from the World Trade Center, and its officials were amazed to find it unscathed from the attacks, according to its website.
This led to being an epicentre of the relief effort, a place for donations for those in need and a place for breaks from the destruction outside.
It took nine months to fully clear the area, which became known as Ground Zero.
Presently, One World Trade Center stands there. It’s a two-minute walk away from The National 9/11 Memorial Plaza .
Chaplain Rev Mychal Judge was one of the 343 serving members of the New York Fire Department who lost their lives on 9/11. According to the Irish Times, he was the son of Irish-Catholic immigrants in Brooklyn during the Great Depression.