A gasp could be heard at a campus news conference when Virginia Tech Police Chief W.R. Flinchum said at least 20 people had been killed. Previously, only one person was thought to have been killed.
Investigators from the federal Bureau of Alcohol, Tobacco, Firearms and Explosives began marking and recovering the large number of shell casings and will trace the weapon used, authorities said.
A White House spokesman said President Bush was horrified by the rampage and offered his prayers to the victims and the people of Virginia.
"The president believes that there is a right for people to bear arms, but that all laws must be followed," spokeswoman Dana Perino said
After the shootings, all entrances to the campus were closed, and classes were canceled through Tuesday. The university set up a meeting place for families to reunite with their children. It also made counselors available and planned an assembly for Tuesday at the basketball arena.
After the shooting began, students were told to stay inside away from the windows.
Aimee Kanode, a freshman from Martinsville, said the shooting happened on the fourth floor of West Ambler Johnston dormitory, one floor above her room. Kanode's resident assistant knocked on her door about 8 a.m. to notify students to stay put.
Police said there had been bomb threats on campus over the past two weeks by authorities but said they have not determined a link to the shootings.
According to Chris Gorman, a student at the university, the campus was in a state of shock already by mid-morning amid rumors that numerous students had been killed and many others wounded.
"We had that guy who killed some police officers on the first day of classes, and recently there have been a lot of bomb threats," added Gorman.
It was second time in less than a year that the campus was closed because of a shooting.
Last August, the opening day of classes was canceled and the campus closed when an escaped jail inmate allegedly killed a hospital guard off campus and fled to the Tech area. A sheriff's deputy involved in the manhunt was killed on a trail just off campus. The accused gunman, William Morva, faces capital murder charges. [See previous story on Morva incident on SecurityInfoWatch.com]