The last two people to be pulled alive from the destroyed World Trade Centre today told how they were saved by a pair of handcuffs.
Port Authority Police officer Will Jimeno and Sgt John McLoughlin were virtually dead centre in the 16-acre complex when the first building collapsed, burying them in debris.
They were part of a group of five Port Authority officers who were rushing to collect rescue equipment from lockers to be sent up a freight elevator to help firefighters when they were buried.
Two of the group died immediately and a third, Dom Pezzulo, started to push rubble off his body.
But as he did, the three men felt the building shake.
Mr Jimeno told the New York Times he shouted at his friend: "Dom, it's going to go", only for the officer to be crushed to death by the rubble from the second tower collapsing.
The two men were left unable to move and were trapped completely by the rubble.
"Concrete across my chest, my leg, and a cinder-block wall on my right foot," said Mr Jimeno.
Sgt McLoughlin asked him: "Can you see sky?" and his colleague replied: "No sky, but light" as he peered through a hole in the rubble above him.
An hour after the second collapse, Mr Jimeno heard a voice.
"The person said 'Is so-and-so down there?' I said 'No, but Jimeno and McLoughlin PAPD are down here'," said Mr Jimeno.
But they heard nothing more from the voice and were forced to wait as balls of fire fell towards the tiny hole they were trapped in, miraculously not setting either man on fire.
Mr Jimeno, 33, said he thought he was about to die, and thought about his wife Allison, who was expecting their second child in November.
"I asked God to let me see my little unborn child, and somehow, in the future, to let me touch this baby."
The two waited for hours when, at 8pm, a voice above them said: "United States Marines. If you hear us, yell or tap."
Mr Jimeno shouted: "Over here."
The marine was Reserve Sgt David Karnes, an accountant, who had rushed into his uniform when he saw the towers collapse.
Unable to contact police and firefighters as he searched in the site, he used his mobile phone to call his sister in Pittsburgh, Pennsylvania, who phoned local police, who then passed the message to New York emergency services.
Sgt Karnes and three other rescue workers, including a paramedic and two emergency service officers, crawled into the tiny hole, while a firefighter pushed fire back from the pit.
But they were unable even to fit in a shovel and Scott Strauss, one of the emergency services officers, searching for something to dig with, saw Mr Jimeno's handcuffs, which he had dropped earlier in the day.
Mr Strauss used them to dig at the debris, opening the hole enough for rescue equipment to be passed down to free the two men.
After a three-hour struggle, with firefighters warning 4 World Trade Centre, one of the smaller buildings, was about to collapse and Mr Strauss lying on top of him, Mr Jimeno was freed.
But it would be another seven hours before Sgt McLoughlin was freed by a fresh team of rescuers, making him the last person to be pulled alive from the rubble.