With more than 25,000 full-time students, Virginia Tech has the state's largest full-time student population.
Police said there had been bomb threats on campus over the past two weeks but that they had not determined whether they were linked to the shootings.
It was second time in less than a year that the campus was closed because of gunfire.
Last August, the opening day of classes was canceled when an escaped jail inmate allegedly killed a hospital guard off campus and fled to the Tech area. A sheriff's deputy was killed just off campus. The accused gunman, William Morva, faces capital murder charges.
Among the dead were professors Liviu Librescu and Kevin Granata, said Ishwar K. Puri, the head of the engineering science and mechanics department. Librescu, an Israeli, was born in Romania and was known internationally for his research in aeronautical engineering, Puri wrote in an e-mail to The Associated Press.
Puri called Granata one of the top five biomechanics researchers in the U.S. working on movement dynamics in cerebral palsy.
"My father blocked the doorway with his body and asked the students to flee," Joe Librescu said in a telephone interview, citing e-mail he said students had sent to his family. "Students started opening windows and jumping out."
Also killed were: Emily Jane Hilscher, 19, of Woodville; Mary Karen Read, 19, of Annandale; Ross Abdallah Alameddine, 20, of Saugus, Massachusetts; and Daniel Perez Cueva, 21, a native of Peru, friends, local officials and relatives said.
Ryan Clark, a student from Martinez, Georgia, was also among the victims, said Vernon Collins, coroner in Columbia County, Georgia. Clark was a resident assistant at the dorm where the first shootings took place.
Gregory Walton, a 25-year-old friend of Clark's who graduated last year, said he feared the nightmare had just begun.
"I knew when the number was so large that I would know at least one person on that list," Walton said. "I don't want to look at that list. I don't want to.
"It's just, it's going to be horrible, and it's going to get worse before it gets better."
Associated Press Writer Justin Pope in Blacksburg contributed to this report.