A Bicester computer expert has told how he fled the crumbling World Trade Center as it was attacked by terrorists.

John Butler was staying in the Marriott Hotel, linked by its first eight floors to the north Tower -- the first to be struck by a hijacked plane -- when the attack took place.

Mr Butler, who has a wife Shirley and two-year-old son Ryan, arrived in New York the day before the attack to give a presentation to his employers -- American computer company, Unisys.

Commercial manager, Mr Butler, 39, said: "I had just gone down for breakfast in the hotel restaurant at the bottom of Tower One. We heard a terrific bang and immediately thought it was a bomb attack. "Debris began falling on the glass roof and we all moved out into a courtyard. I fell over, gashed my left leg and hurt a shoulder.

"There was a rumble and shaking like an earthquake coming down through the hotel. Bits of glass from the restaurant roof fell into our hair.

"We moved into a courtyard between the towers but as debris was falling there we moved into the basement of Tower Two, which we thought might be reasonably safe.

"I hobbled along with the help of a colleague. But we decided we had better get out of Tower Two and reach a hospital. We still did not know what had really happened." Mr Butler, of Ravencroft, Langford Village, Bicester, allowed his friend, who had a good knowledge of New York, to lead him to a hospital.

He added: "By the time Tower Two was attacked we were two blocks away. We did not see the aircraft crash into it, but we saw the plume of flames and smoke coming out of the side of the building.

"When we reached a hospital near Broadway a huge cloud of dust and smoke was coming over. The hospital staff had to close all the windows and doors to try and keep the dust out. They even put a big fan in the entrance to blow the dust out."

Hospital staff dealt with his gashed leg but he was unable to leave for two hours because of the mayhem with people fleeing the crumbling towers.

He said: "The dust cloud covered everything. People were handing out bottles of water to people who were covered by the dust." Mr Butler believes that if he had gone to breakfast five minutes later he could have been killed as the hotel collapsed along with the twin towers.

"I think it was fate. I lost everything I had in the room," he said.

He and his office colleagues were eventually re-located to a hotel in Pittsburgh until he was able to fly home the following Saturday. When he was able to watch television, he realised how lucky he had been. "I was absolutely flabbergasted to see the television film of the attacks. I was only able to get away because the attacks on the towers were separated by 20 minutes or so."

Mr Butler was unable to telephone and let his wife know that he was safe for several hours.

"Shirley knew that I was in the hotel. But all the telephones were down," he said.

"It was not until a few hours later that I was able to get through to her and let her know I was safe. I am still shaken by the experience."