A 76-year-old Jewish-Romanian lecturer was hailed a hero after blocking his classroom door long enough for many of his students to escape the Virginia Tech gunman, before being shot dead.

Liviu Librescu, a Holocaust survivor, pressed himself against the door of the classroom while shots were fired in the corridor and surrounding rooms. He stood firm, attempting to barricade the door, while his students clambered out of the windows.

His son, Joe Librescu, said in an interview from Tel Aviv that the professor e-mailed his wife to say that he had prevented the gunman getting into the classroom. However, the next e-mails received by the family were from students in the class informing them that Mr Librescu had not survived the shootings.

“My father blocked the doorway with his body and asked the students to flee,” Joe Librescu said. “Students started opening windows and jumping out.”

Alec Calhoun, 20, from Waynesboro, Virginia, was one of the students to escape from Librescu’s class. When they heard the screams and gunshots, he and his classmates kicked through the screens on the second floor windows.

Mr Calhoun believes he was the last person to leave the room before the gunman struck. “I must’ve been the eighth or ninth person who jumped, and I think I was the last,” he said. The two students behind him and his teacher blocking the door were shot according to Mr Calhoun.

Richard Mallieu, 23, from Virginia was another student watching an engineering slideshow given by Librescu when Cho Seung-Hui began shooting in the Norris Building. He admitted: "I don't think my teacher got out."

On the God Bless Virginia Tech blog set up by students while the massacre was under way, one poster wrote of Librescu: “What a wonderful man, a survivor, and a hero. He will be missed!”

Librescu was born in Romania only to be interned in a labour camp when it joined forces with Nazi Germany in the Second World War. He was then sent to a ghetto in the city of Focsani, although he avoided the fate of hundreds of thousands of other Romanian Jews killed by the collaborationist regime.

He later found work at a government aerospace company but his career was stymied in the 1970s because he refused to swear allegiance to the regime of the Communist dictator Nicolae Ceausescu.

In 1977, according to his son, Israel’s then-prime minister, Menachem Begin, personally intervened with Ceausescu to get the family an emigration permit, and they left for Israel in 1978.

Professor Librescu had arrived in Virginia in 1985 for a sabbatical, but decided to stay on as a teacher.

In a neighbouring building a British student, George Barnwell, 20, was also able to send a message to his family. He was on campus with his British girlfriend, Claire Harrison, while the shooting took place.

George’s mother, Jenny, said: “Both incidents were close to where they were - the second was in the engineering building where George would often be. Fortunately he wasn’t at the time. It makes you realise how fragile they are when something like this happens.”

Mr Barnwell, from Birmingham, is on a year’s exchange at Virginia Tech from Sheffield University where he is studying mechanical engineering.

Virginia Tech students set up various websites and online notice boards where the names of the missing were posted. One by one names were ticked off the missing list as friends sent messages confirming they were safe. More posts implored readers to send information on their own missing friends.

The first name to be moved into the “Deceased” column was Ryan Clark, as the hours passed more students were reported to have died, with accompanying messages such as “RIP bud”.

Even the Virginia Tech online football forum became a medium for students wanting the latest information on their friends and organising vigils and marks of respect.

One blogger spoke to his girlfriend at hospital, who “still has a piece of a bullet lodged into her hand, and has fractions on her index and pinky finger. Right as she picks up the phone she tells me ‘I got red on me’.”

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