Published Thursday, 08 September 2011
Almost 3,000 people were killed in the co-ordinated suicide attacks on the United States in 2001.
Two planes hijacked by Al Qaeda crashed into the twin towers of the World Trade Centre, with hundreds of lives lost inside the burning office blocks.
A third craft was directed into the US government's Pentagon building in Virginia while a fourth, United Airlines Flight 93, came down in a field in Pennsylvania after passengers attempted to retake control.
Eugene McNaulty was a firefighter living on the edge of New York when the attacks happened.
The Warrenpoint man reported for duty as the towers were falling. Hundreds of his colleagues were amongst those who lost their lives that day.
"We did find body parts but no actual survivors," he says, speaking of the fire crews' rescue efforts at Ground Zero.
"On occasions when we did come across a body everybody would stop and we'd drape an American flag over whatever the remains were and just carry the body out, giving it as much respect."
As they worked there were fears the buildings would collapse around them killing even more people, while the sheer amount of dust also hampered efforts.
Mr McNaulty says rescuers are still feeling the effects of the toxic smoke they breathed in.
"The dust was horrific, in fact it turned out to be treacherous," he said.
"It's only several years later the public know how dangerous this particular dust was.
"There have been hundreds of people dying from the toxic dust and the chemicals they were exposed to - and it's shameful what the firemen and policemen are going through nowadays to get medical coverage and what their families."
Out of 9/11 came the war on terror.
The hunt for the man who masterminded the attacks, Osama Bin Laden ended in May, when he was tracked down and killed at his base in Islamabad, Pakistan, by US forces.
Almost a decade on, Mr McNaulty says he's still trying to make sense of it all.
"When I see the kids of the fathers who died that day, that's the hard part," he said.
"Whatever trouble that I and everybody else have in life, at least we still have our parents but these young kids don't.
"They don't have their fathers any more, some don't have their mothers also. Just the sheer devastation that day, almost 3,000 people died and for what?"