The survey found nearly half of all threats were bomb threats (44 percent) and close to 30 percent of the threats caused school evacuations. The vast majority were hoaxes.

The firm stressed the negative impact these threats have on students, staff and police departments. It also noted the rising role of electronic communication in school threats. More than a quarter of all threats were made through social media (28 percent).

It appears no school is immune, says Ken Trump, president of National School Safety and Security Services. Here are the top 10:

1.      Ohio: 64

2.      California: 60

3.      Pennsylvania: 55

4.      New York: 46

5.      Florida: 43

6.      Texas: 41

7.      Michigan: 36

8.      Washington: 37

9.      Massachusetts: 34

10.  Connecticut: 29

Bomb and shooting threats make up the majority, and that is where school administrators and police should focus their preparations and planning, says Trump.

• Bomb: 359, 44 percent
• Shooting: 234, 29 percent
• Death: 26, 3 percent
• Knife: 9, 1 percent
• Hit list: 6, 7 percent
• Unspecified: 214, 26 percent

Trump found that electronic devices and social media apps are fueling the growth of these threats, especially with new, anonymous apps that young people are rapidly adopting; 299 threats (37 percent) were sent electronically, using social media, email, text messaging and other online resources. Social media threats, alone, account for 231 threats (28 percent). Threats are often posted on Twitter, Facebook and Instagram.

Trendy apps like Yik Yak, After School and Whisper are creating special problems for investigators because teens can post anonymously, making it harder to track down offenders, says Trump. These apps account for 45 threats across the country so far this school year.

There were seven references to "swatting," a growing phenomenon of calls triggering massive police responses for hoax threats. Several cases crossed state and international borders. While high schools received 70 percent of threats, middle schools got 18 percent, and elementary schools got 10 percent. Six percent of threats were leveled at entire school districts, sending thousands of children home or putting them in lock-down or lock-in status inside their classrooms, according to Trump.

Almost 30 percent of the threats involved schools being evacuated and nearly 10 percent closed school for at least the day of the threat. Threats are causing a substantial disruption of learning and school activities. Improved threat assessment and crisis communications preparedness can help school administrators avoid premature evacuations and unnecessary closings so learning may continue when hoax threats strike a school, says Trump.

Police have made at least 320 arrests so far this year, says Trump. The vast majority are children, ranging in age from 8 to 18.  

While local law enforcement officials were involved in the vast majority of these incidents, Trump says he found an emerging presence of federal law enforcement involved in school threat incident investigations. Almost 40 incidents (5 percent) referenced federal investigative agencies with the majority of them being the FBI.

Trump’s recommendations include:

• Teachers and administrators need to create a trusting and connected school climate that will give them an early warning when rumors get started.
• Educators and parents have to understand how kids use social media, and educate them about the harm that threats can cause.
• School officials and police should use threat assessment protocols to determine if a threat is credible. This will reduce unnecessary evacuations and closings.
• Solid crisis communication plans that give parents real-time information can greatly reduce anxiety, and get schools and parents working together. School districts should survey their parents to find out which communication channels they use and meet them there.
• Communities need an easy way for kids, parents and schools to report threats and safety concerns using the latest electronic tools.