At age 76, Librescu was among the thirty-two people who were murdered in the Virginia Tech massacre. On April 16, 2007, Seung-Hui Cho entered Norris Hall Engineering Building and opened fire on classrooms. Librescu, who taught a solid mechanics class in Room 204 in the Norris Hall during April 2007, held the door of his classroom shut while Cho was attempting to enter it. Although he was shot through the door, Librescu prevented the gunman from entering the classroom until most of his students had escaped through the windows. He was struck by five bullets, with a shot to the head ending his life. Of the 23 registered students in his class, one, Minal Panchal, died.
A number of Librescu's students have called him a hero because of his actions. One student, Asael Arad, said that all the professor's students "lived because of him." Caroline Merrey, a senior, said she and about 20 other students scrambled through the windows as Librescu shouted for them to hurry. Merrey, previously seated in the rear of the room while next to the windows, stated that she was the third student to leave Norris 204. Merrey said that "I don’t think I would be here if it wasn't for [Librescu]."Librescu's son, Joe, said he had received e-mails from several students who said he had saved their lives and regarded him as a hero while many newspapers also reported him as the hero of the massacre.
Following the murder of Librescu, his son Arieh contacted the Chabad movement to secure that his father's body would be treated according to Jewish law and that the body was released immediately for Jewish burial in Israel. With the assistance of Gov. Timothy M. Kaine, the body was released on April 17 and brought to New York via police escort. On April 18, Librescu received a funeral service at a Jewish Orthodox funeral home in Borough Park, Brooklyn, New York City, New York and on April 20, he was interred in Israel. In his native Romania, his picture was placed on a table at the Polytechnic University of Bucharest, and a candle was lit. People laid flowers nearby.
Marlena Librescu stated that her husband's favorite Jewish commandment was that Jews should light Shabbat candles. On Friday eve April 20, 2007, the Chabad movement spearheaded a campaign to light Shabbat candles. Following the funeral, the Chabad on Campus Foundation announced their intention to establish a chapter in Librescu's name at Virginia Tech.
The murder took place on Holocaust Remembrance Day (Yom HaShoah). On April 18, 2007 U.S. President George Bush honored Librescu at a memorial service held at the US Holocaust Museum to a crowd that included many Holocaust survivors:
That day we saw horror, but we also saw quiet acts of courage. We saw this courage in a teacher named Liviu Librescu. With the gunman set to enter his class, this brave professor blocked the door with his body while his students fled to safety. On the Day of Remembrance, this Holocaust survivor gave his own life so that others may live. And this morning we honor his memory and we take strength from his example.