(NewsNation) — In the wake of a shooting an elementary school in Nashville, Tennessee, schools across the country have seen a wave of hoax calls claiming there is a shooter.

It pulls police from actual emergencies, it shows a school’s vulnerabilities and it can be psychologically draining. Hoax school shooting calls, or swatting calls, are happening at an alarming rate.

It’s been called the “second curse of school shootings.”

“From my perspective, this is a form of terrorism,” former FBI intelligence analyst Jennifer Doebler said.

On Tuesday, more than two dozen Massachusetts schools were the targets of swatting calls. On Wednesday, first responders responded to calls regarding schools in Utah, Pittsburg, Southern California and Kansas, the list growing throughout the day.

When the calls come in, schools and law enforcement take action. Students barricade themselves in classrooms and parents find themselves receiving nightmarish phone calls.

The calls claiming to report an active shooter were all fake. But the emotional effect is real, especially when the hoaxes come on the heels of a real shooting, like the one at Covenant elementary school that claimed the lives of three children and three adults.

“This is a way to inflict pain and terror on local communities, on families. It’s also a way to drain resources. It’s a way to learn about communities and what their responses are. It’s a way to occupy law enforcement resources for long periods of time,” Doebler said.

Swatting isn’t a new phenomenon, but the practice is becoming more common.

It’s a complicated issue because police have to respond in full force. Aside from the psychological impact on children and families, fake threats and hoaxes can be a drain on law enforcement resources, particularly in rural communities.

To complicate issues more, it’s difficult to even track the exact number of crimes because the FBI does not track swatting as its own crime. But estimates of swatting cases in U.S jumped from 400 cases in 2011 to more than 1,000 in 2019, according to the Anti-Defamation League.

One key difference between the calls from then and today is technology. Previously, offenders did not have the capabilities to mask numbers or use a voice-over IP service to make calls.

In a press release Wednesday regarding the series of swatting calls in Western Pennsylvania, Pennsylvania State Police said all the calls “had had similar content.” The calls were also computer generated.

“And so it was much easier to identify perpetrators and to hold them accountable. It’s a wildly different, different situation. Now, many times these swatting incidents come from overseas,” Doebler explained.

Doebler’s own family was recently the victim of swatting.

“It’s something that our community is still feeling. Even a month later, as we continue to watch things happen in other parts of the country. It’s not just financial, it takes a mental and emotional toll on communities for long periods of time they go far beyond the morning or the day of the incident,” she said.