There have been at least 12 threats against schools across the nation since a mass shooting Wednesday at a Florida school, according to a news analysis by McClatchy.
It’s not uncommon for a mass shooting — such as the one that killed at least 17 and injured 15 more at Marjory Stoneman Douglas High School in Parkland, Florida — to inspire others.
Up to 30 percent of mass killings can be traced back to other ones from the past 13 days, according to a 2015 study from researchers at Arizona State University and Northeastern Illinois University.
The researchers wrote: “Several past studies have found that media reports of suicides and homicides appear to subsequently increase the incidence of similar events in the community, apparently due to the coverage planting the seeds of ideation in at-risk individuals to commit similar acts.”
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For example, the deadly 1999 shooting at Columbine High School (13 dead and 24 injured) inspired at least 21 similar attacks and 53 plots or threats that were stopped by law enforcement, according to an analysis by Mother Jones.
A security expert told the magazine that “it’s a cult following unlike anything I’ve ever seen before.”
The Broward County Sheriff’s Office, which responded to the Parkland, Florida, shooting, sent out a message Thursday about potential copycats.
There has also been a rise in threats leveled against schools across the U.S., according to a 2015 study from the National School Safety and Security Services. The study found that there were 812 bombing and shooting threats made against schools from August to December 2014 — a 158 percent increase from the year before.
Seventy percent of the threats were made against high schools, the study found.
Here are some of the threats reported against schools since the Wednesday shootings in Florida, though not all have been determined to be copycat efforts.
Spartanburg County, South Carolina
A school received extra security on Thursday following a social media threat, according to WYFF. The Spartanburg County Sheriff’s Department received an anonymous tip Thursday from a student about a threat posted against Broome High School on Snapchat.
A ninth-grader at the campus has been arrested on suspicion of disturbing schools, reported the station. The teen posted a Snapchat photo of himself holding a firearm captioned “Round 2 of Florida tomorrow,” reported WHNS.
South Portland, Maine
Police arrested a 15-year-old South Portland High School student Thursday after a threat about “shooting up the school” on Snapchat, according to WMTW. He was arrested on suspicion of terrorizing and carrying a concealed weapon. The teen was carrying a knife, police said.
Oklahoma City, Oklahoma
Western Heights Public Schools were on high alert Thursday morning after a threat against one school by a student, according to KFOR. “We have made contact with the police and we have supplied information including photos to all school sites and our security staff. We have heightened security measures today and will be vigilant about the safety of our students and staff,” the district wrote on Facebook.
Charleston, West Virginia
Students and teachers arrived at George Washington High School on Thursday to a large police presence after a social media threat, reported WSAZ.
A police spokesman told the station that a student responsible for the threat has been identified.
Backpacks were searched at North Middle School on Thursday after a threat made against the school on social media, according to The Gleaner. Extra officers also were on duty at the school.
Seven Teton County Sheriff’s Office deputies responded to Teton High School on Thursday after an anonymous tip received late Wednesday night, according to The Teton Valley News. The tip said someone was bringing a gun to school.
San Diego, California
San Diego police said they were “confident that there are no credible threats” after a student at Scripps Ranch High School made threatening comments on Wednesday night, according to Fox5.
Nicole DeWitt, the school’s principal, sent a message Thursday morning about the threat to parents and students at the California school, which will have an extra police officer on duty.
Macon County, North Carolina
Macon County Schools announced that a 16-year-old student was arrested after he made threatening comments about “the safety and well-being of fellow students” Wednesday afternoon while exiting a school bus.
“The threats made yesterday were extremely serious in nature and all of our staff took the appropriate steps immediately following the statements,” School Superintendent Chris Baldwin and Sheriff Robert Holland said in a statement. “Threats of any kind against students and/or faculty will not be tolerated.”
Wendell, North Carolina
A threat made Wednesday against Corinth Holders High School in the wake of the Florida school shooting was determined to be not viable, but officials are investigating why parents were not informed, according to WNCN.
Le Mars, Iowa
Police say they arrested a 14-year-old after he left a threatening note in a LeMars High School classroom Wednesday afternoon, leading to a school lockdown, according to The Sioux City Journal. No one was harmed, Superintendent Steve Webner said in a release.
Lehigh Valley, Pennsylvania
Threats in a letter led to a lockdown at Southern Lehigh High School on Wednesday, according to LehighValleyLive.com. A student has been arrested on suspicion of terroristic threats and false reports to law enforcement.
Fair Haven, Vermont
Fair Haven Union High School was placed on restricted access Wednesday night after a threat, according to MyChamplainValley.com. Police said the threat was not credible but an investigation continues.
Schools across the nation also are dealing with a wave of rumors and false reports of threats.
In Elyria, Ohio, police reported that a threatening message posted to Snapchat by an Elyria High School student turned out to be lyrics to a rap song and not an actual threat, reported The Cleveland Plain Dealer. The lyrics, which referenced guns and being “not afraid to die,” came to police attention when a concerned parent called police at 1 a.m. Thursday.
In Carmel, Ind., educators on Wednesday emailed parents to say reports of a safety threat at Carmel High School are just a rumor, according to The Indianapolis Star. Police have investigated and found no credible threat to the school, administrators wrote.