Bomb scares will cost New Jersey schools about $2.1 million this year, according to an analysis this month of school bomb threats.

But school officials say they are acting prudently in the face of unknown danger.

"School bomb threats are an issue for school communities throughout the state of New Jersey," Edward Dickson, director of the state Office of Homeland Security and Preparedness, wrote in a May 17 letter to the State Police, prosecutors, police chiefs and school superintendents. The analysis was prepared by Dickson's agency.

"Although the majority of school bomb threats turn out to be pranks, school districts and law enforcement agencies must take each threat seriously because of the potential for injury and loss of life," Dickson wrote.

There were 61 bomb threats between Sept. 1 and May 17, an increase of 27 percent from the previous school year, which saw 44 threats.

All were unfounded. However, Dickson's memo said the bomb scares create significant costs, disrupting schools and diverting money from education budgets away from the intended purpose.

They also ties up emergency resources that cannot be used elsewhere.

The analysis showed most of the threats occurred at high schools, on Mondays or Thursdays and predominately in northern New Jersey.

Notes, followed by graffiti were the two most common ways to make a threat.

The largest number of threats were made in April, followed by March and January, but the memo noted a sharp uptick after the April 15 Boston Marathon bombing.

There have been a number of incidents in South Jersey over the past year.

A person was charged with making a false public alarm after a bomb threat suspended the first day of school at Atlantic Cape Community College on Sept. 4.

Two 16-year-old Oakcrest High School students were arrested and charged with making threats against the school on April 17, following threats found at the school on April 10 and 16.

Both threats led to school evacuations while bomb-detecting dogs searched the building.

Both students were charged with creating false public alarms, making terroristic threats and conspiracy.

Several area school officials declined to comment when contacted, saying they feared that speaking about threats would invite more of them.

"I think that everyone just has to respond a little more cautiously," said Tom Baruffi, superintendent for the Mainland Regional High School District. "I guess how some people may have responded 10 to 15 years ago is a little bit different than they would today."

As an example, he said, a threat was brought to him early one morning in January. A Washington, D.C., man with no obvious ties to the school said there would be unspecified violence at Mainland and other schools in Burlington and Camden County.

Baruffi decided to close school for the day.

"I got no complaints that we decided to not have school that day," he said. "I think the general population feels there is a better safe than sorry mentality out there."

The school has seen other incidents, including a 15-year-old sophomore girl from Linwood who was arrested Dec. 19 and expelled from school after passing along a text message to a friend saying there would be a shooting at school.

The charges were dropped two months later and she was reinstated.

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