Liviu Librescu

Professor Liviu Librescu, 76, an Israeli engineering and math lecturer, was known for his research, but his son said the Holocaust survivor will be remembered as a hero for protecting students as the gunman tried to enter his classroom.

Librescu taught at Virginia Tech for 20 years and had an international reputation for his work in aeronautical engineering.

"His research has enabled better aircraft, superior composite materials, and more robust aerospace structures," said Ishwar K. Puri, the head of the engineering science and mechanics department.

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Joe Librescu talks about his father, Liviu

, a Virginia Tech professor who died trying to save his students from gunman Cho Seung-Hui.

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Librescu's son, Joe, said his father's students sent e-mails detailing how the professor saved their lives by blocking the doorway of his classroom from the approaching gunman before Librescu was fatally shot.

"My father blocked the doorway with his body and asked the students to flee," Librescu's son, Joe Librescu, said Tuesday in a telephone interview from his home outside of Tel Aviv. "Students started opening windows and jumping out."

A funeral service was held for Librescu on Wednesday, April 18, in Brooklyn, N.Y. On Friday, family and friends gathered at a cemetery in Ra'nana, Israel to remember the professor as a survivor, and bury him as a hero.

Librescu's body lay wrapped in a traditional white Jewish funeral shroud, surrounded on one side by family, and on the other by media photographers.

Through tears, Librescu's widow Marlena said she has received many e-mails from Virginia Tech students saying their lives were saved by her husband, reports CBS News correspondent Robert Berger.

"I will never know what passed through your mind in the last moments, but I hope you take care of your family from where you are now," she said at the service.

Librescu's son, who stood at his mother's shoulder, came to the microphone and said, "I walked today with my head up, proud having such father. I'm just proud of you, father."