(NEW YORK) -- Before Sandy Hook Elementary School in Newtown, Conn., became synonymous with "massacre," it seemed to have done everything right. It kept its doors locked when classes were in session, required visitors to sound a buzzer to enter the building, and conducted lockdown drills. But Adam Lanza still managed to shoot out a window and blast his way into the school, killing 20 first-graders, six adults and later himself last December.
In the aftermath of the massacre, there's been plans to tear down Sandy Hook and replace it with a new school with heightened security on the same property.
"I think our understanding of safety in public schools has changed," Newtown First Selectman Pat Llodra told ABC News. "The state of Connecticut will come out with new standards, [and] we will certainly comply and probably exceed those standards."
Taking a page from the Newtown mass shooting, school districts across the country have invested millions of dollars in increasing security measures to ensure that they do not experience a tragedy like Newtown's.
"I think nationwide we all kind of see Newtown as a game-changer," Rex Barrett, the acting director of security for Prince George County School District in Maryland, told ABC News. "It's changing school security dynamics the way 9/11 changed travel."
Prince George Public School District has invested $7.5 million in enhanced security measures, said Barrett. Part of the funding comes from the state. Maryland Gov. Martin O'Malley has incorporated $25 million into the fiscal 2014 state budget to go toward school security. The Prince George County Public School District is using $3.3 million of that grant, more than double what it would usually spend, said Barrett.
The funds make it possible for the county to equip every school with closed-circuit television systems, cameras, electronic entry systems and panic buttons. All security officers will also be trained in mediation and resolution so they can try to resolve initial conflicts before they escalate.
"We've always thought these things were important, but after Newtown, everything had to be put on the fast track," said Barrett. "Instead of taking three years we want it done this school year."
Frank Belluscio, the deputy executive director of the New Jersey School Board Association, said that while the security in Garden State schools has always been "top-notch," the schools are now reviewing safety protocols and allocating funds to increase security in light of Newtown.
"Newtown brought a different dimension, [the idea that] an intruder comes in spite of all your safety measures. It made school districts want to look for ways to improve security," he said.
For example, Belluscio explained, on the day of the shooting, Lanza was outside the school. As a result, local New Jersey police departments will make periodic checks around schools for any suspicious activity.
Belluscio also said there was a strong interest in having video surveillance, and adhesive placed over the windows of school buildings, which can help block bullets. Nearly 200 schools had incorporated security video surveillance through March 2013, according to the website of 3M Safety and Security Films.
Belluscio could not provide a dollar figure on the amount of money New Jersey schools had invested in security since Newtown, and calls to the New Jersey Department of Education's Office of School Preparedness and Emergency Planning went unreturned.
The fight for tighter security has also made its way into state legislatures, with hundreds of bills, including proposals to increase police presence, update emergency plans, arm school employees and provide counseling. More than 450 school-security bills had been introduced in statehouses across the country as of May 23, according to an analysis by Education Week.
"There is no doubt that since the tragedy of Newtown, there is a heightened sense of need to improve school safety measures," California Assemblywoman Kristin Olsen, an advocate of tightening school security measures, told ABC News.
Connecticut, the state most personally affected by Newtown, is putting in place a policy to increase security measures in all Connecticut schools. Gov. Dan Malloy announced in May that Connecticut would be distributing $5 million to schools for additional security measures. All public schools were eligible for funding, and the money will be used to reimburse schools that upgrade their security measures.
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