The investigation: Students at Virginia Tech demanded to know yesterday why they had been allowed to proceed to classes after the first shooting incident in one part of the college campus, but before the second and more deadly rampage had begun.
What happened between 7.15am on Monday, when a 911 call was made to police reporting the initial shooting, and 9.45am when gunfire was heard elsewhere on the campus, has become a focal point for the investigation and for questions about whether more could have been done to prevent the carnage.
Most of the deaths - 30 of the 32 students who died - happened in the second incident at Norris Hall or because of injuries incurred there. A student, Kevin Tosh asked: "Why was I allowed to go to class?" He had been in the Ambler Johnston dormitory when the first shooting happened, but did not hear it.
"It was still early and officials were not around. But the police could have warned us. We feel the police should have locked down the campus."
But other students defended the authorities. "There is only one person accountable for what happened yesterday, and that is the gunman," said Teresa McCall, a nutrition student.
Details about the time between the shootings remain sketchy. What is known is that when police arrived at the dormitory and found Emily Hilscher and Ryan Clark dead, they assumed a domestic murder had been committed by someone they had reason to believe had left the campus and was attempting to escape.
That assumption appears to have drawn police attention away from the campus, leaving them surprised when the second shootings occurred. Officers were interviewing an acquaintance of Ms Hilscher, whom they had stopped in a car outside the campus, when news of the second shooting reached them.
But should they have closed down the campus, as they had done in August last year when an escaped convict shot dead a police officer near the college grounds?
Students also wanted to know why it took more than two hours for them to be sent a warning e-mail. The e-mail was sent at 9.26am. "A shooting incident occurred at West Amber Johnston earlier this morning. Police are investigating," it stated.
The message warned students to be cautious and contact police about anything suspicious.
The college also says that a siren was sounded, though students said they did not hear it or did not understand what it was for. But the campus was not blocked off and classes were not cancelled, leaving students to stream into the science and engineering block, Norris Hall, about a mile away from the dormitory, where Cho Seung-Hui later opened fire.
College president Charles Steger said it was not easy to close the college with its 26,000 students and 100 buildings. "We had no reason to suspect another incident was going to occur," he said.
- (Guardian service)