RICHMOND, Va. &#8212 Virginia Tech’s president, facing calls for his ouster, defended his university’s response to the nation’s deadliest school shooting, saying Thursday that officials couldn’t have known the gunman would attack twice.

“Nobody can say for certain what would have happened if different decisions were made,” President Charles Steger told a news conference.

“The crime was unprecedented in its cunning and murderous results,” he said.

A governor-appointed panel that investigated the April 16 massacre at the Blacksburg campus released a report late Wednesday criticizing Virginia Tech officials, saying they could have saved lives if they had acted more quickly to warn students about the first shootings that morning at a dormitory and that a killer was on the loose.

Instead, it took administrators more than two hours to send students and staff an e-mail warning. The shooter had time to leave the dormitory, mail a videotaped confession and manifesto to NBC News, then return to campus and enter a classroom building, chain the doors shut and kill 31 more people, including himself.

“Warning the students, faculty and staff might have made a difference,” the panel in its report. “The earlier and clearer the warning, the more chance an individual had of surviving.”

Steger said the administration was responding during the hours that passed after the first two students were slain in the dormitory.

“The notion that there was a two-hour gap is a great misconception,” Steger said. “There was continuous action and deliberations from the first event until the second, and they made a material difference in the results of the second event.”

“Cho is responsible for the carnage,” he said. “In respect to suggested changes, we recognize, as does the panel, that no plausible scenario was made for how this horror could have been prevented once he began that morning.

“I am not aware of anything the police learned that would have indicated that a mass murder was imminent.”

One victim’s mother urged the governor to “show some leadership” and fire Steger, and other parents demanded accountability for the errors.

Gov. Timothy M. Kaine, however, said the school’s officials had suffered enough without losing their jobs.

“I want to fix this problem so I can reduce the chance of anything like this ever happening again,” the governor said. “If I thought firings would be the way to do that, then that would be what I would focus on.”

Kaine said instead that parents of troubled children who are starting college should alert university officials, and those officials should “pick up the phone and call the parent” if they become aware of unusual behavior.

“The information needs to flow both ways,” the governor said.

The eight-member panel, appointed by Kaine, spent four months investigating the attacks.

It found that even before the killings, the university had failed to properly care for the mentally troubled student gunman, Seung-Hui Cho.

“The alert should have been issued and classes should have been closed,” the panel’s chairman, Gerald Massengill, told the AP Thursday.

The first two victims were shot in the dormitory shortly after 7 a.m. It wasn’t until 9:26 a.m. that the school sent an e-mail to students and faculty warning: “Shooting on campus. The university community is urged to be cautious and are asked to contact Virginia Tech Police if you observe anything suspicious or with information on the case.” Cho opened fire inside Norris Hall about 20 minutes later.

Derek O’Dell, who was shot in the arm at Norris Hall, said he probably wouldn’t have gone to class that morning if he had known that there was a killer on the loose.

“I don’t think anybody would have,” he said.

But the panel also concluded that a lockdown of the 131 buildings on campus would not have been feasible. And while the first message sent by the university could have gone out at least an hour earlier and been more specific, Cho likely still would have found more people to kill, it said.

“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.