Inside Norris, the attack began with a thunderous sound from Room 206 - "what sounded like an enormous hammer," said Alec Calhoun, a 20-year-old junior who was in a solid mechanics lecture in a classroom next door.
Screams followed an instant later, and the banging continued. When students realized the sounds were gunshots, Calhoun said, he started flipping over desks to make hiding places. Others dashed to the windows of the second-floor classroom, kicking out the screens and jumping from the ledge of Room 204, he said.
"I must've been the eighth or ninth person who jumped, and I think I was the last," said Calhoun. He landed in a bush and ran.
Calhoun said that the two students behind him were shot, but that he believed they survived. Just before he climbed out the window, Calhoun said, he turned to look at his professor, who had stayed behind, apparently to prevent the gunman from opening the door.
The instructor was killed, Calhoun said.
Erin Sheehan, who was in the German class near Calhoun's room, told the student newspaper, the Collegiate Times, that she was one of only four of about two dozen people in the class to walk out of the room. The rest were dead or wounded, she said.
She said the gunman "was just a normal-looking kid, Asian, but he had on a Boy Scout-type outfit. He wore a tan button-up vest, and this black vest, maybe it was for ammo or something."
The gunman first shot the professor in the head and then fired on the class, another student, Trey Perkins, told The Washington Post. The gunman had a "very serious but very calm look on his face," he said.
"Everyone hit the floor at that moment," said Perkins, 20, a second-year mechanical engineering student. "And the shots seemed like it lasted forever."
At a Monday evening news conference, Police Chief Wendell Flinchum refused to dismiss the possibility that a co-conspirator or second shooter was involved. He said police had interviewed a male who was a "person of interest" in the dorm shooting and who knew one of the victims, but he declined to give details.
Some students bitterly complained that the first e-mail warning arrived more than two hours after the first shots.
"I think the university has blood on their hands because of their lack of action after the first incident," said Billy Bason, 18, who lives on the seventh floor of the dorm.
University President Charles Steger emphasized that the university closed off the dorm after the first attack and decided to rely on e-mail and other electronic means to spread the word, but said that with 11,000 people driving onto campus first thing in the morning, it was difficult to get the word out.
He said that before the e-mail was sent, the university began telephoning resident advisers in the dorms and sent people to knock on doors. Students were warned to stay inside and away from the windows.
"We can only make decisions based on the information you had at the time. You don't have hours to reflect on it," Steger said.
The 9:26 e-mail had few details: "A shooting incident occurred at West Amber Johnston earlier this morning. Police are on the scene and are investigating."
Until Monday, the deadliest shooting in modern U.S. history was in Killeen, Texas, in 1991, when George Hennard plowed his pickup truck into a Luby's Cafeteria and shot 23 people to death, then himself.
Nine students remained hospitalized Tuesday at Montgomery Regional Hospital, all of them stable, CEO Scott Hill said. Two others had been transferred to other hospitals with a Level I trauma center.
Lewis-Gale Medical Center in Salem had three remaining patients, all in stable condition, with one expected to be discharged later Tuesday, Hill said.
The massacre Monday took place almost eight years to the day after the Columbine High bloodbath near Littleton, Colorado. On April 20, 1999, two teenagers killed 12 fellow students and a teacher before taking their own lives.
Previously, the deadliest campus shooting in U.S. history was a rampage that took place in 1966 at the University of Texas at Austin, where Charles Whitman climbed the clock tower and opened fire with a rifle from the 28th-floor observation deck. He killed 16 people before he was shot to death by police.