The scene inside the Blacksburg campus was captured on video by one of the students. Rapid gunfire can be heard between the buildings.
The sequence of events around the shootings is now clear. It seems the gunman fled a dormitory after shooting dead a male and female student. But he did not kill his other victims until more than two hours after those first shots.
An investigation is being demanded into the police response.
Students were sent an email to warn them that a gunman was on the loose, but nothing was announced on the PA system.
The Principal of the Virginia Tech University insists he did all he could, in the circumstances.
“We locked down the building. We thought the incident was contained. We had no reason to suspect there was any other danger.”
But no steps were taken to evacuate the campus.
Those first deaths took place at 7am. Two hours later the gunman went to the science and engineering building and shot 30 students and staff with a handgun before turning the weapon on himself.
Police said he had chained doors shut to prevent people escaping. Some were hurt jumping from windows.