The unprecedented school massacre at Virginia Tech has underscored one terrifying fact: Such attacks can never be completely prevented, and college campuses are especially vulnerable.

That was the admission by universities of all sizes and types around the country, at which security and disaster experts weighed in only hours after a gunman's shooting spree left at least 32 dead and at least 15 injured at the Blacksburg, Va., school.

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"How easy is it? Based on my experience, if you're really intent on committing a crime, you can do it," said John Gildard, director of safety and security at Marist College, a small, private liberal arts school in a rural setting about 75 miles outside of New York City.

The director of police community services at the large, sprawling campus of the University of California at Los Angeles echoed those sentiments.

"The reality is, at UCLA we have many precautions and we work consistently with the campus community on preventing crime, but as long as we live in a democratic society, there's always an underlying vulnerability," said Nancy Greenstein.

Though there are limits as to what schools can do to prevent such crimes and heighten security — public universities and colleges, for example, aren't allowed to have gated access to campus, because they're public — there are safety measures schools can and do take.

Among them: Controlled access to residence buildings in the form of student ID swiping machines; guards at academic and dormitory buildings; a strong campus police and security presence; active-shooter training for officers and guards; metal detectors and bag searches at athletic and other events that attract crowds; security cameras; trained student guard forces; and education about safety procedures for students, faculty and staff.

All of those policies are in effect at Rutgers University in New Brunswick, a large suburban campus with more than 34,000 students (50,000 total at the school's three main locations), and at UCLA, an urban state school with a total of 37,000 students (more than 10,000 of whom are residents of the university).

"I don't think incidents like this can be prevented. I think the best you can do is try to minimize the impact they have and make it as unattractive to come here as possible," said Rutgers University New Brunswick's Chief of Police Rhonda Harris.

Harris said that she has 58 sworn officers — meaning all are trained as state police and are fully armed — on her force. They patrol campus 24 hours a day, seven days a week via car, bicycle and ATV, as well as on foot. The Rutgers Camden and Newark campuses have their own police units, she said.

In addition to police, Rutgers New Brunswick has a security department of about 35 officers plus a student component of 110 security-trained students who are "the eyes and ears of the security force," according to Harris.

Community services officers are used to conduct bag searches and provide additional support at sports and other events that attract large numbers of attendees.

More than 1,000 security cameras have been installed throughout campus — which has 895 buildings, not including dormitories — and the university is "continuing to implement that," Harris said. Some of those cameras are monitored regularly at certain dates and times of the week, all have the ability to record so that officers can go back and review footage and some stream video into the university's dispatch center.

"Should we get any call, we can pull that camera up and begin to monitor live" an incident that is under way, Harris explained.

All dorms have controlled access in the form of student ID machines, and some have human monitors at the front desk during specific hours.

"We're very proactive with what we do here," said Harris. "We do have a procedure in place for what actions officers should take in an active-shooter situation. They seek out and engage anyone with a weapon or who is firing a weapon on campus."

The situation is similar at UCLA, which also has a sworn police force of state officers who train at the sheriff's academy and carry weapons, according to Greenstein. She declined to release the number of officers, citing security reasons.

The UCLA force, like that at Rutgers, is trained to handle school massacre situations, she said.

"Here, our officers receive continual training in active-shooter scenarios," Greenstein said. "You want well-trained, professional staff ... You try to identify the problem and mitigate whenever possible before it becomes more serious ... It's not just one thing, but a multitude of approaches that works the best."

There's also a small staff of university security guards, and community service officers help out when needed, according to Greenstein. Metal detectors and wands are used for some events, especially those with high-profile attendees.

Even smaller campuses like Marist and Bloomsburg University in rural Pennsylvania have tight security measures in place.

Bloomsburg recently increased its safety procedures after the Sept. 11, 2001, terrorist attacks and an incident this past fall where someone shot a gun into the air during a crowded outdoor gathering, said communications director Liza Benedict.

Though it's a small school of only about 8,000 students in a town whose population is only 12,000, the police force there is sworn and armed, she said, and a portable metal detector was recently purchased for large-scale events.

"After that student event, it absolutely made us beef up our security ... We are so aware of the shooter possibility," said Benedict. "I'm sure we're not alone in this. We have a crisis planning team, an emergency preparedness team."

Unlike the other universities, Marist is a private school — and its security force is also private rather than state authorized with police powers, meaning officers there can't carry weapons but do work closely with local Poughkeepsie, N.Y., law enforcement, Gildard said.

"We're very fortunate here. We've never had any major incidents," he said of the school of 4,000 undergraduates — 3,000 of whom live on campus. The college has 67 officers on staff, according to Gildard.

Though tragedies like that at Virginia Tech can never be completely eradicated, universities should make sure to inform their students and faculty of danger and get them involved whenever possible, said Rutgers disaster sociologist Dr. Lee Clarke.

"If somebody is very determined, given that we don't have effective gun control, they can do some damage," he said. "We're wide open, and major universities are terrific targets.

"But when the world falls apart, it's the person next to you who's going to save you. In spite of fears of panic and mayhem, people can be trusted with frightening news."

Virginia Tech officials and police have already come under fire for not placing the campus on complete lockdown immediately after the first, early-morning shooting. The second spree, during which the bulk of the victims were killed, took place about two hours later — and many students were unaware of the first incident or of any danger on campus at all.

The university has said it believed the first crime was an isolated, domestic case, may not have been related to the second shooting and was under control — even though police and administrators have admitted they didn't have the gunman in custody.

But it's possible that the investigation will reveal Virginia Tech could have done more to alert students of what was going on — and possibly prevent the shooting from being as catastrophic as it was, according to Clarke.

"If the story is true that the guy went into a dormitory, did some damage and then two hours later was doing damage in another place and nobody was warned," said Clarke, "that will be a major organizational failure."