The death toll in the worst mass killing in modern U.S. history could have been lower if Virginia Tech officials had acted more quickly, a panel said. But the school's president dismissed suggestions he should be held accountable for the killings.
Seung-Hui Cho, 23, killed 32 people before turning his gun on himself.
"No plausible scenario was made for how this horror could have been prevented once he began that morning,'' Virginia Tech president Charles Steger told reporters.
Some family members of the victims have called for Steger to resign, like William O'Neil, whose song Daniel was fatally shot by Cho.
"In my view of the world, the buck stops at the top," he told The Associated Press. "I think that in this case, his lack of leadership and his lack of compassion for the families is just astounding."
A panel that spent four months probing Cho's deadly shooting spree on April 16 in Blacksburg, Va., released its report on Wednesday.
The panel found that school administrators failed to act quickly enough after Cho began shooting.
It found that the university waited more than two hours before warning students that the initial double-homicide had taken place and two students had been shot. Lives may have been saved if administrators had acted faster, the report states.
But Steger told reporters Thursday he would have done nothing differently.
"I am not aware of anything the police learned that would have indicated that a mass murder was imminent," he said. "The panel researched reports of multiple shootings on campuses for the past 40 years and no scenario was found in which the first murder was followed by a second elsewhere on campus. Nowhere."
But Gov. Timothy Kaine, who appointed the panel, said it is clear some things should have been done differently.
"In the immediate aftermath of the first shooting at the dormitory the ...community should have been notified of the fact that there was a fatal shooting and the fact that a perpetrator or perpetrators were still at large and had not been apprehended," Kaine said.
He said a committee process was in place to render a decision about issuing notifications, but there was no way to sidestep the process and issue a warning faster than the two-hour committee process.
"The committee convened as promptly as they could and weighed the evidence and then issued a notice, but the notice came too late," Kaine said.
By that time, Cho had turned up on the other side of the campus, where he killed 30 other students and teachers, methodically gunning them down in a classroom building.
Kaine said the report should serve as a blueprint for changes to be made at campuses everywhere.
The panel's report suggested an early warning would have helped protect students and faculty, it said it would have been difficult to lock down all 131 buildings on the campus.
And the report pointed out that although the initial warnings to people on campus could have been issued at least an hour earlier and offered more specific details about the situation, Cho probably would have still continued his shooting spree.
"There does not seem to be a plausible scenario of a university response to the double homicide that could have prevented the tragedy of considerable magnitude on April 16," the report said. "Cho had started on a mission of fulfilling a fantasy of revenge."
The panel, consisting of eight members appointed by Kaine, has spent the past four months looking into the how the massacre was handled and what could have been done differently.
There had been multiple warning signs that all was not well with Cho in the days, months and years leading up to the worst shooting in modern U.S. history.
Cho had displayed signs of suicidal and homicidal tendencies and mental health problems dating all the way back to middle school, in the post-Columbine High School shootings in 1999.
He was put on medication and received some counselling at the time, but then in a creative writing class in 2006 he wrote a paper about a young man who plans to kill his fellow students and himself.
The university did not act on the grim paper, despite an earlier referral to the counselling service in 2005 due to bizarre behaviour and concerns he would attempt suicide.
"Unfortunately, none of that information about his fixation on Columbine -- about his mental health history, about the fact that he could succeed if he had targeted intervention -- ever got to Virginia Tech," said Kaine during a Thursday news conference.
"And I think that was a huge missed opportunity. And I think it's probably pretty common that students walk on to college campuses all over this country with a college campus possibly knowing something about their GPA or their SAT score, maybe an essay, but not really understanding fully what the student may need in order to succeed."
The report said a lack of resources, misinterpretation of the privacy laws and passivity all contributed to the high death toll.
The panel said officials "did not intervene effectively. No one knew all the information and no one connected all the dots."
The report had good things to say about the police and emergency service response to the dormitory shootings, calling it "prompt and effective."
However, the report also suggested university police may have erred in prematurely concluding that the first two shootings were the result of a domestic dispute.
Diane Strollo, whose daughter Hilary was shot but survived, suggested an earlier warning from the university could have saved lives.
"Had some or all of the student body been notified that two students were gunned down that morning, they may have had heightened sensitivity to the sound of gunshots and other suspicious activity," she wrote in an email to The Associated Press.
"One or two minutes of notice may have been critical in saving more lives in Norris Hall."
With files from The Associated Press
