Survivors tell their stories on 20th anniversary of 9/11 terror attacks

Amid the tragedy there were stories of courage and hope and co as an estimated 33,000 or more people successfully evacuated the stricken buildings on Tuesday September 11 2001.

They navigated smoke filed stairways in New York's World Trade Centre's twin towers or streamed out of a flaming Pentagon

Engineer and lawyer Bruce Stephan was one of the lucky ones.

He was working on the 65th floor of the trade centre's north tower when one of the planes crashed about 30 storeys above.

Only after his hour-long walk down the crowded stairs did Mr Stephan learn that another plane had hit the south tower - the building where his wife, Joan, also an attorney, worked on the 91st floor, above the impact zone.

It would be hours before the two were reunited.

Mr Stephan, 65, said: "It's almost like you're reborn ... to know that you're alive and that you still have a shot at life."

Aon Corp worker Desiree Bouchat managed to escape from the 101st floor of the south tower.

She said: "Some days, it feels like it happened yesterday.

At first, people believed the plane crash at the north tower was accidental.

There was no immediate evacuation order for the south tower. But Ms Bouchat's colleague, James Patrick Berger, ushered her and several other workers to the elevators, then turned back to check for more people.

Just as Ms Bouchat exited the south tower, another plane slammed into it. Nearly 180 Aon workers perished, including Mr Berger.

For a while, she said she told everyone, including herself: "I'm fine. I'm alive."

But "I was a walking zombie," she said.