Families of two victims in the Sandy Hook Elementary School shooting have filed a wrongful death lawsuit against the town of Newtown, Conn., and its board of education, alleging security measures at the school weren't adequate.

The two families' motivation was solely to improve school security for future students in the Newtown school district, Donald Papcsy, an attorney for the families, said in a statement on Monday.

For years schools have been trying to find ways to become more safe and prevent the next shooting, but the task is easier said than done, expert say, especially in a way that doesn't scare young students or disrupt the learning environment.

In the wake of the 1999 shooting at Columbine High School in Littleton, Colo., districts renovating and building schools studied what they could do to make them safer, architect Irene Nigaglioni tells CNN.

Schools began to build single, prominent entryways with bare landscaping, providing fewer places to hide. They moved restrooms away from entrances, Ms. Nigaglioni says, and installed elaborate announcement systems that let police address a shooter without speaking to every classroom.

On its website, the National Association of School Psychologists offers a list of ways a school can make itself a safe learning environment, including installing an alarm system and/or closed-circuit television monitoring system, minimizing blind spots, trimming trees and shrubs to limit outside hiding places, mixing faculty and student parking, and securing fences with heavy-duty padlocks.

In Newtown, the gunman, Adam Lanza, parked his car less than 100 feet from the school entrance on Dec. 14, 2012. He entered through doors near the school's main offices, where he killed the principal and school psychologist. He then entered two classrooms and killed 20 students and six educators, before fatally shooting himself, according to state police. Before going to the school, Mr. Lanza killed his mother in their Newtown home.

According to the lawsuit, a teacher in one of the two classrooms where students were killed was a substitute, didn't have a key to the classroom door, and didn't receive training on the security protocols. The lawsuit also charges the town with negligence for not having bulletproof glass on the school's front windows, not having doors that could be locked from the inside, and not having parking lot security.

Katherine Newman, provost of the University of Massachusetts at Amherst, and co-author of the book "Rampage: The Social Roots of School Shootings," says that while quick security upgrades like bulletproof glass might help against an attack similar to the Newtown shooting – when an assailant came from outside the school – most school shootings are very different and involve students who are already past security and inside the school.

"I think it’s unfortunately not likely to make a huge difference if our efforts are all designed at a law enforcement or security response," Provost Newman says.

Newman adds that she doesn't think physical security measures, like the bulletproof glass mentioned in the lawsuit, are bad ideas, just that they don't neutralize the threat of an internal shooter, a student who would already be inside a fortified school.

"They’re not mutually exclusive. I would never say avoid bulletproof glass," says Newman, "as long as it doesn’t lull you into thinking the internal threat would be avoided because of it."

Kenneth Trump – president of National School Safety and Security Services, a school security consulting firm – wrote a blog post last week describing how technological "quick-fixes" and investments in physical security equipment wouldn't be able to solve the school safety issue.

The Sandy Hook shooting, he wrote, "sent federal, state, and local education and public safety officials scrambling to 'do something, do anything and do it fast.' "

"Once they get past the 'Wow!' factor of a few dozen new cameras in their local high school, most people are stunned to find out that many of these schools and school districts have no budget set aside for the repair and/or replacement of these cameras once they are damaged or have technical malfunctions," continued Mr. Trump.

"The result: A facade of enhanced security," he said, describing the common physical security measures as "an oversimplified response to a complex human public safety problem."

Other efforts to address school safety have focused on trying to increase communication and awareness among educators and students, so potential threats are identified and people can receive help before a shooting happens.

A May 2013 report from the US Secret Service details several such measures, including building relations between adults and students and ensuring that students, parents, teachers, and staff are familiar with how to report behaviors and communications that are of concern.

Newman adds, "The only way you can protect people from something that happens in a matter of seconds is to try and track it in advance."

Such approaches, which can involve hiring special employees and end up being more expensive than physical security measures, can stretch the already limited budgets of most schools.

"Most school districts feel strapped one way or another," says Newman.

Most school shooters fit the profile of Adam Lanza, Newman says, and she believes that many could be stopped by being identified and treated long before they reach the point of taking a gun to school. Lanza's parents, educators, and others missed signs of how serious his mental health problems were, according to reports by state police and the state child advocate.

In an August 2012 article in the Baltimore Sun, Newman wrote that "we cannot successfully profile these shooters," and thus hope to stop the rare and tragic event that is a school shooting.

"Even the FBI gave up trying to profile them, and that agency is in the business of predicting rare events," wrote Newman at the time. "The only real hope for preventing rampage shootings is to increase the likelihood that kids who are witness to these hints of what is to come are able to come forward and tell someone."