ELMWOOD, N.J. – Nearly two dozen New Jersey schools in 14 towns received bomb threats this week, marking at least the fourth round of widespread calls since January.

Passaic County Sheriff’s officials were discussing bomb threats with students at Passaic High School Wednesday morning when they were interrupted by the most recent round of automated bomb threats at other schools, several of which were closed for spring break, NorthJersey.com reports.

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Police officials evacuated students from some schools, where they were taking standardized tests, and most were back to class by noon. At others, authorities put the buildings on lockdown to search for bombs, NBC New York reports.

“Schools in northern New Jersey have been targeted by threats many times in the last several months. In January, 11 schools received robotic-sounding voicemail messages routed through California that alluded to explosives or mass shootings,” according to the news site.

“In Bergen County alone, there have been 31 bomb threats at schools since January, not including Wednesday’s threats. Sixty-four schools were searched in those threats.”

The previous year there were a total of 16 bomb threats, officials said.

In a prepared statement about the most recent calls, the Bergen County Prosecutor’s Office said officials are “looking into how they fit into the prior swatting events.”

Passaic County Sheriff’s spokesman Bill Maer told North Jersey that Passaic High School was not among those that received threats Wednesday, but the school has received eight threatening calls so far this year.

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“The department does not see a link between the presentation and these calls since similar calls were done in neighboring counties,” he said.

Several news sites have covered the repeated mass-scale bomb threats this year, as well as the school presentation Wednesday, and Leonia police Capt. Scott Tamagny believes the coverage could be contributing to the problem.

“I think it’s absolutely possible they’re reading the stories,” he said, “that they’re looking for fame and notoriety and that’s why they continue to do these.”

Most of the calls seem to come during the morning hours, feature a robot voice, and allege there is a bomb in the school or a vehicle in the parking lot. Some of the calls are unspecific about which school was allegedly targeted, forcing district officials to evacuate multiple schools.

Elmwood Park’s board of education, for example, received a call at 8:21 a.m. Wednesday claiming a bomb was in one of the schools and in the parking lot, and the district covers six schools, North Jersey reports.

“Because it was non-specific, we had to treat it as if it could have been any of those schools,” Elmwood Park Police Chief Michael Foligno said.

The robocall bomb threats are not unique to New Jersey.

Numerous schools in Massachusetts, Iowa, Delaware, Maryland, Virginia other states have experienced the same phenomenon this school year. Several schools in those states also received threats this week.