9/11: New York firefighter who lost 100 friends in attack says they knew they were likely to die
A firefighter with New York City Fire Department for 18 years, who had been at the forefront of the rescue efforts following the 1993 World Trade Center attack, Tim Brown knew what it was to face danger.
But nothing prepared him or his colleagues for the harrowing events of 9/11.
Mr Brown's story of that day is one of "heroes and horrors," he says.
He helped evacuate hundreds of workers safely from the South Tower before it collapsed 56 minutes after United Airlines 175 crashed between floors 77 and 85.
But many of his colleagues did not make it out.
Mr Brown lost more than 100 friends, including his two closest colleagues Captain Terry Hatton and Captain Patrick Brown, in the Twin Towers attack.
He describes the 20th anniversary as "like a monster", a milestone he is keen to see the other side of.
"All these firefighters and police officers knew they were going into this very difficult situation, and that they would likely not be coming back," he tells ITV News.
"We talked about it. My best friend Terry had hugged me, and he kissed me on the cheek, and he said to me, 'I love you brother. I may never see you again'.
"And then he turns, and he went to the stairwell with his men.
"All these firefighters and police officers knew that there was a very good chance that they were going to die that day, and they still did it, they still went up the stairwells, and they still saved people who they did not know and then gave their own lives.
"In the Bible it says that's the greatest example of love that a human could show another human. And it was displayed by the hundreds of September, law enforcement officers and the firefighters of New York." There are many images from that day that are engraved on his mind, from those people trapped in lifts to the firefighter he saw crushed to death by a woman who had been forced to jump.
ITV News US Correspondent Emma Murphy hears the stories of those impacted by 9/11
While the horrors of 9/11 will live with him for ever, so will the heroes.
"There were lots of examples of love. And as everyone knows, systems of unity, were literally worlds came together here at Ground Zero to help each other to love each other to support each other. And it was a very patriotic time, and very sadly I feel like those times are gone."
He now dedicates his time to ensure his friends, and the nearly 3,000 others who were killed that day are never forgotten.