Originally Published: 14 FEB 23 17:41 ET

By Tim Callery

Classes were well underway in New Hampshire schools on the morning of Dec. 8 when a 911 call was made, claiming there was an active shooter at a school.

It was the first of several 911 calls made across the state that day that were all hoaxes.

At 9:50 a.m., 911 dispatchers received a hoax call about an active shooter at St. John's Regional School in Concord. The caller claimed to be a math teacher at the school and said five students had been shot.

Law enforcement officers responded immediately.

"It took less than three minutes for SWAT to arrive on the scene," said Lisa Zolkos, assistant superintended for the Diocese of Manchester and interim principal at St. John's.

Zolkos was sick at home when she got the alert.

"There's a drop in my stomach, and you think about the kids and their safety," she said.

As Zolkos raced to the school, the SWAT team moved in, making their way through the campus and over to a neighboring church where teachers and students were gathered for Mass, unaware officers were circling the building.

"There was a SWAT member that entered the church and spoke with a first-grade teacher and explained there was an active shooter situation on the campus," Zolkos said.

At the same time, police departments across the state started receiving similar calls, from Dover to Portsmouth to Laconia.

"We joined forces with the school principal, their administrative staff," Laconia Police Chief Matt Canfield said. "We were able to quickly locate the room that the caller referenced, and we were able to verify that it was a closet and that there was nothing occurring at that time."

Nothing was going on in any of the cities and towns that received similar calls. Law enforcement officials determined the calls were all part of a hoax, a growing trend across the country.

"Typically, what we're seeing a lot of now is, although they are still coming in via voice phone calls, a lot of them are being done via social media, email and things like that," FBI special agent Tim Demann said.

As for who's behind them, there are a number of possibilities.

"These are folks that could be overseas. There could be folks that don't like the place that that they're making the hoax threat at," Demann said. "Maybe there's a student that wants to get out of school or something like that and wants to make the threat. There could be some financial gain in making the hoax threat."

While there was relief that the calls weren't real, law enforcement officials said such threats still have serious consequences.

"We take every one of them seriously, because we don't know if they're true or not," Canfield said. "So, the possibility of having another incident, a real incident, occur and having resources allocated somewhere else is a very real detriment to a police response."

So far, there are no suspects named in the case.

"We will partner with the U.S. Attorney's Office here in New Hampshire to see if there is a charge that can be placed on the individual," Demann said.

While that December day was nerve-wracking and emotional for administrators, students and their families, it also offered a lesson, officials said.

"Many of our schools used that as an opportunity, a real-world opportunity, to review all of their emergency operation plans, look at the memorandums of understanding with their local police departments, provide training for their staff and implement additional security measures," said Alison Mueller, of the Diocese of Manchester.