Wounded students hold off killer.(THE GOODNESS OF AMERICA)

Derek O'Dell, a 20-year-old biology major, was in a German class in a second-floor Virginia Tech classroom. Hearing a gunshot, he turned his head and witnessed the terrible effects of a bullet striking the head of a male classmate. Incredulous, he at first suspected a prank.

"And then I saw the blood," he related in an interview with the New York Post. "And I knew it wasn't a joke."

As Derek dove under his desk, the gunman--later identified as Cho Seung-Hui, a 23-year-old English major and South Korean native from Centreville, Virginia--walked in and sprayed students sitting in the first row with gunfire. The professor, Christopher "Jamie" Bishop, was also struck and killed.

In an interview with the New York Times, Trey Perkins, a 20-year-old mechanical engineering student from Yorktown, Virginia, who was also in the German class, recalled: "We got down, tried to get on the ground. There were a couple of screams, but for the most part it was eerily silent, other than the gunfire."

Derek was too stunned by what he witnessed to realize, at first, that he had also been hit in the arm. "He was just shooting randomly," he explained. "My arm was hanging out.

"After the gunman left, Derek wedged his foot against the door to prevent the killer from reentering. He tied his belt around his arm as a tourniquet to stop the bleeding. Two other students, a young man who was uninjured, and a young woman who'd been shot in her hand, helped Derek block the door.

Trey Perkins said: "It was just amazing to me that [Derek] was still up and leaning against the door. Derek was able to hold him off while I was helping other people."