U.S. public schools beefed up security measures with safety drills and parent notification systems in the years surrounding the massacre at Connecticut’s Sandy Hook Elementary School, according to a government survey released Thursday.

The uptick came during a four-year span that saw an overall decrease in violent crime reported by schools, but one that included high-profile incidents such as the Newtown, Connecticut, shootings in December 2012 that left 20 children and six educators dead.

The findings, from the 2013-14 school year, come from the National Center for Education Statistics.

The survey found that 88 percent of public schools had a written plan of how to respond to an active shooter, and that 7 out of 10 had drills to practice the plan. About three-quarters of schools reported using security cameras, and 43 percent said they used security personnel at least once a week.

Even before the Newtown killings, schools had been working more closely with local law enforcement and ramping up other school security measures, said Ronald Stephens, executive director of the National School Safety Center.

“I think something like Sandy Hook certainly punctuates the need to engage additional security strategies, but I really see it as an ongoing trend,” he said.

Stephens said he believes the work has been a factor in a decrease in overall school crime.

The survey showed 65 percent of public schools reporting one violent incident in school, such as a rape, fight, robbery or threat of physical attack. That’s down from 74 percent in the 2009-10 school year, when the survey was last administered.

The findings were based on a survey sent to school principals. Among the other results:

—About 8 in 10 schools reported having a parent notification system that automatically notifies parents in case of an emergency, compared with about 6 in 10 four years earlier.

—Slightly less than half — 47 percent — of schools reported having a system that allowed someone to report a crime anonymously, compared with 36 percent four years earlier.

Despite the reported decreases in violent school crime, Ken Trump, a school safety consultant, said personnel in the schools he has visited don’t have a sense that the number of incidents is going down.

“We’re hearing people saying we’re having a lot more problems with aggressive kids and such,” Trump said.

(AP)