Julio Cortez / AP file

Community members will have to decide whether eventually to reopen Sandy Hook Elementary School after a gunman killed 20 children and six adults on Dec. 14.

Classes are set to resume Tuesday in Newtown, Conn. -- everywhere but at Sandy Hook Elementary School, where a gunman shot and killed 20 children and six adults on Friday.

The school has been closed indefinitely, authorities said Monday, while law enforcement officials process the crime scene, a grim task that could take months. 

But what happens after the investigation to the site at 12 Dickinson Drive remains in unclear. Whether it can -- or should -- reopen to serve 525 kindergarten through fourth-graders depends on how the community and the children respond, experts say.

For now, some local parents say it’s too soon to tell.

“I haven’t even given it any thought,” said Andrew Paley, 40, of Sandy Hook, father of 9-year-old twins Ben and Ethan, both Sandy Hook students who were at the school during Friday’s rampage. 

Students from Sandy Hook are set to begin classes soon at Chalk Hill School in nearby Monroe, district officials said. The building has not been used as a school for 18 months, according to local press reports, and is being renovated quickly to accommodate the Sandy Hook classes. Though there is no firm date for them to start in the new site, being together in class should help students begin to heal, experts said.

It’s important for young children to resume normal routines as quickly as possible, said Amy Smith, president of the National Association of School Psychologists.

“For kids to recover from an event like this, they need to be safe and they need to believe they are safe,” Smith said. 

But whether the student Sandy Hook students at those kids -- or any children -- can return to the Sandy Hook site, a building where youngsters and adults were shot, most multiple times, is doubtful, said Dr. Liza Gold, a clinical professor of psychiatry at Georgetown Medical School.

“You have to think about what’s going to help these kids most in terms of regaining a sense of safety and minimizing the effects of trauma,” Gold said. “You can’t bring them back to that school. You have to think of it as a place that has been contaminated.”

Across the U.S., schools and other venues that have been the site of mass shootings have had to grapple with the question of what to do with the buildings.

For some, it’s been a matter of removing all signs of carnage and getting students back to class as quickly as possible. At Thurston High School in Springfield, Ore., the cafeteria that was the site of a 1998 shooting opened less than a week after freshman Kip Kinkel opened fire, killing two students and wounding 24.

But at Columbine High School near Littleton, Colo., the school was closed for four months after an April 1999 shooting that killed 12 students and a teacher, plus the two gunmen, Eric Harris and Dylan Klebold. The school’s library, where much of the attack occurred, was replaced with an airy atrium and a new library was built elsewhere on campus.

Virginia Tech’s Norris Hall, the primary site of a 2007 shooting that left 32 victims and the gunman, Seung-Hui Cho, dead, eventually was reconfigured and renovated. The second floor space was turned into the school’s center for Peace Studies & Violence Prevention, said spokesman Mark Owczarski.

“In essence, the building continues,” he said. “It has a new life, a new look.”

In Aurora, Colo., the movie theater where gunman James Holmes killed 12 people and injured 58 in July will reopen next month, according a letter from Tim Warner, president and chief executive of Cinemark. The company made the decision to refurbish the Aurora Century Theater after surveying the community. Victims and their families will be invited to the site to visit before the opening on Jan. 17. 

But some spaces have not been reclaimed. The one-room Amish schoolhouse that was the site of a 2006 shooting was razed after Charles Roberts opened fire on a dozen girls barricaded inside, eventually killing five. A new schoolhouse was built on a different site in Nickel Mines, in Lancaster County, Pa., according to press accounts.

“I thought there was a widespread feeling in the community that it was important to remove the building,” community spokesman Herman Bontrager told USA Today at the time. “Especially for the children, but not only for the children.”

Only time will tell if the Sandy Hook Elementary School site can be resurrected enough to feel safe for kids, said Gold.

“If you think about a workplace setting, adults could work through that trauma,” she said. “A little kid might not even understand what is disturbing to them.”

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Those who commit mass murders are often angry and isolated, but usually aren't mentally ill, violence experts said Friday after a shooting during the midnight screening of "The Dark Knight Rises" in an Aurora, Colo., movie theater. James Holmes was arrested as a suspect in the shooting that killed 12 people and wounded 59 others.

“It takes a certain degree of clear-headedness to plan and execute a crime like this,” said James Alan Fox, a criminal justice professor at Northeastern University in Boston, who has written several books on mass murder and school violence.

There are exceptions – Jared Loughner, who shot and killed six people in Arizona in 2011, gravely injuring then-member of Congress Gabrielle Giffords, was diagnosed with schizophrenia. Mental health experts say people with mental illness are not any more likely than anyone else to become violent, however.

Mass murderers “often times feel that they are right and everybody else is wrong,” Fox said in a telephone interview. “They really tend to externalize blame, to see other people as responsible for their problems."

They are often socially isolated. “They tend to be a failure at life,” Fox added.

12 dead, 59 injured in Colorado movie theater shooting

Such well-planned attacks are rare and not meant to make a statement, Fox said. “They basically want revenge,” he said.  “Contrary to the common misperception that these guys suddenly snap and go berserk, these are well-planned executions.”

The film the victims were watching is loaded with violence but it’s unlikely that actually inspired the attacker, Fox said. The film was opening that night and it’s doubtful the attacker was familiar with the script.

“It was just coincidental, although it just made the situation more ambiguous for the people involved,” he said. Some of those who were in the theater said they initially first thought the shooting was part of the screening. 

Early reports suggest Holmes did not have a police record and the University of Colorado has confirmed he was in the process of dropping out of a Ph.D. program in neuroscience there.

Former FBI profiler Clint van Zandt  told TODAY that Holmes was almost certainly acting alone. “Today, so far, he appears to be … the lone wolf,” Van Zandt said. The attack was carefully planned, both Van Zandt and Fox said, which fits the patterns of such attackers.

“They typically plan carefully how they are going to do it, where they are going to do it, what they are going to bring and what they are going to wear,” Fox said. In this case, the victims were not deliberately chosen, although the place, a packed movie theater, probably was.

The attack may encourage copycat actions but not necessarily, Fox said. “What bothers me in situations like this is to see lists of the worst mass shootings,” he said. “It encourages people to try to break records.”

Dr. Victor Schwartz, medical director of the Jed Foundation, which works to promote mental health among college students, agreed. “The media needs to be really careful in these situations,” he said. “On the one hand, you need to report the story. On the other hand, there is the danger of sensationalizing it, almost romanticizing the drama here.”

Schwartz also advises resisting any attempts to speculate on whether violent videos or movies may have affected Holmes. “The research slants both ways,” he said. Some studies suggest that children who watch and play violent videos may become desensitized to some aspects of violence, but there is not a clear consensus.

“None of these things is caused by a single factor,” Schwartz said. “Obviously, these are always very complicated events. The impulse is to find a simple explanation for complicated situations. It is important to resist it.”

Experts say it’s almost impossible to predict attacks like this one. “Neighbors will come forward and say it was no surprise,” Fox said. “But it’s all after the fact. Beforehand, even though someone may fit a profile, we can’t predict they will do this sort of crime. It’s a very rare event and not predictable. That’s part of what makes it so scary.”

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