It used to be that a "Visitors must report to the office" sign was enough.

That was before multiple shootings at Columbine High School, Virginia Tech and other schools made the conversation surrounding school security at all levels more urgent. 

The events of Dec. 14, 2012, brought that difficult conversation closer to home. Adam Lanza, 20 at the time, used a semi-automatic AR-15 assault rifle to shoot his way into Sandy Hook Elementary School in Newtown, killing 20 first-graders and six educators before turning the gun on himself.

In the aftermath, sections 86 and 87 of Public Act 13-3 became law, giving all public school districts in the state until July 1, 2014, to create school security and safety committees and to develop school security and safety plans.

The plans must be reviewed, updated if necessary, and submitted to the state annually.

The law also calls on existing safe school climate committees to watch out for disturbing or threatening behavior that "may not meet the definition of bullying" and report it when necessary.

Local districts are at different stages in the process of upgrading security, with progress depending, in part, on their size and ability to obtain state and federal grants.

Some, like Norwich, had basic security measures, such as locked doors, outdoor cameras and intercoms for people at the door, long before the Newtown tragedy.

In North Stonington, major strides have come just in the last few months.

With a security plan — one that involves the town's first selectman and fire, police and other departments — in place since last year, North Stonington Public Schools have put a $103,000 Homeland Security grant toward to make upgrades.

The North Stonington layout is campuslike: Students use an underground pathway throughout the day to get from Wheeler Middle-High School to the central office building, which hosts the two schools' shared gymnatorium and band room.

From his office, Superintendent of Schools Peter Nero said he often sees students heading toward the tunnel, which anyone can access.

"There's no doubt you get nervous looking at the tunnel," Nero said.

In the past, one door on either side of the passageway was always open.

Now, teachers and some students will be given keycards on lanyards to get into buildings. And, in the near future, the tunnel will be one of three campus locations with a blue-light phone pole. Just pressing a button will bring help.

Also new in the schools this year are enhanced security camera and intercom systems, magnetic locking doors and the Raptor School Visitor Management System.

Under the Raptor system, visitors will have to present an ID upon their first visit to each school, entering their names into a database that continually checks for sex offenders.

"You're limited until there's a building project ... but these are things we could do to protect kids as best we could," Nero said. "All these things, whether it's a renovated-as-new or a brand new building, would have to be included, so we feel we're in good shape moving forward."

The sprawling campus at Norwich Free Academy has dozens of buildings, several driveway entrances and a museum open to the public. A school security staff of 19 actively seeks ways to bolster safety at the 2,300-student regional high school.

This summer, NFA upgraded and added to its network of outdoor cameras in both well-traveled and remote locations, now totaling 70.

Over the past two years, the school created check-in gates at two entrances and an automated key card gate at another.

New this year, NFA spokesman Geoffrey Serra said, is a security gate in the driveway behind the Shattuck Building.

The gates are opened after school for public parking for athletic and other school events.

In New London schools, staff response has been the focus.

This summer, New London developed what it's calling an Incident Command Structure, in which Central Office staff members have pre-assigned roles — such as logistics, mental health, safety and communications — that they'll oversee at the district's schools, should there be a crisis.

Additionally, the district has assigned staff from the central office in each building to conduct visual sweeps of every floor and classroom in the event of an evacuation.

The schools already have cameras and buzzer visitor systems in place, as do those in East Lyme, Montville and Preston. Ledyard and Groton added cameras this summer.

In Preston, security measures implemented in the past few years include "911 fobs" worn by staff members to call for emergency service. Staff also carry cellphones that work solely in and around the school buildings.

In Waterford, all of the district's public schools have been renovated or replaced in the last 10 years, and upgraded security in the process.

The school system piloted School Gate Guardian — which, like the Raptor system, runs a background check on visitors before issuing them a badge for the day — in Great Neck Elementary School, and then put it in the other elementary schools as well.

Because the system was successful in the elementary schools, Assistant Superintendent Craig Powers said, the district built into the budget funding to also place it in the middle and high schools this summer.

l.boyle@theday.com

Twitter: @LindsayABoyle

Staff Writers Ann Baldelli, Claire Bessette, Deborah Straszheim and Kimberly Drelich contributed to this report.