ONE survivor of the terrorist atrocities fled the World Trade Centre as it was hit by a hijacked airplane with his sister and young niece on board, his family revealed today.

Ronnie Clifford ran for his life after the first plane struck the twin towers in New York, and escaped the second tower as it was hit by the United Airlines Boeing 767.

In a cruel twist, his sister Ruth Clifford McCourt, 45, and her four-year-old daughter Juliana were passengers on the second plane and died as he escaped.

All 266 passengers and crew on the four planes hijacked were believed to have been killed in the attacks, which have sent the world into shock.

Mrs McCourt, originally from The Lough, Cork, were among 56 passengers on the hijacked plane.

Mr Clifford's brother John told of the deaths and his brother's astonishing escape.

John, also from Cork, said he began fearing for his sister and niece after discovering that his brother was safe.

"Tragically my sister hit the tower building as my brother was on the ground floor. He's safe now. He's very traumatised.

"He said he saw sights he would never see again. Very sad. Very evil, but he's safe," he said.

He continued: "I was very concerned when the two buildings collapsed, because I knew Ronnie worked in one.

"He phoned to say he made it, he was OK, traumatised, that he was within an inch of his life.

"He went through the front door on the ground floor and a lady was about three seconds in front of him. She was hit by a terrific fireball. She subsequently died.

"He said that unfortunately, while he was OK, he had a feeling that his sister - my sister - had left Logan Airport to go to Los Angeles with her daughter at around 7.30 in the morning.

"So we were then concerned that she may have been on either of the two flights that crashed into the towers, and that was confirmed."

A friend of Mrs McCourt, who lived in Connecticut and had gone to Boston to fly to LA for a few days' holiday, was also killed.

Mr Clifford said his sister's husband was absolutely devastated. Juliana was their only child. Mr Clifford said she was a "beautiful" girl and described his sister as "full of life".