Copycat threats after Florida mass shooting spur a New Jersey town to close schools

— -- Copycat threats around the country following the massacre at a Florida high school led at least one school district to close schools Friday.

The district in Nutley, New Jersey, closed public schools Friday and canceled all evening events after officials "became aware of a security threat" late Thursday night, according to a statement by Superintendent Julie Glazer.

"We have decided to err on the side of safety and close schools tomorrow, February 16," Glazer said in the statement Thursday. "As both the superintendent of the Nutley Public Schools and as a parent, and because of the nature of the world in which we live, there was no other decision to be made."

Nutley police are "actively investigating" the threat, Glazer added.

The Nutley Police Department said a video posted to Instagram led them to open an investigation. Police said they spoke with the person who posted the video and that detectives are interviewing people linked to the video as part of the probe.

"The Nutley Police Department is continuing to investigate the video posted to Instagram," Nutley Police Chief Thomas Strumolo said in a press release Friday. "The individual that has been identified in this incident is cooperating with our investigation."

Neither Nutley police nor school officials divulged the content of the video, but Strumolo said it "did not contain a direct threat to any of our schools."

"The facts uncovered in the investigation up to this point indicate that there does not appear to be an immediate threat to any of the schools or the public at this time," the police chief added.

Other threats

Also in New Jersey, in the township of Franklin, a 14-year-old allegedly made a threat on social media against Franklin High School on the night of the Feb. 14, after the mass shooting that day in Florida, which prompted a police investigation. Investigators ultimately determined "this was not a credible threat." The suspect was taken into custody, according to the Franklin Township Police Department.

The student was charged with third-degree terrorist threats and released to his parents. He has been suspended from school, police said.

Authorities in South Florida had warned of possible copycat threats or hoaxes after a gunman opened fire at Marjory Stoneman Douglas High School in Parkland on Wednesday, killing 17 people and injuring dozens more. Broward County Sheriff Scott Israel told reporters Thursday that his agency would treat any such incidents incidents as real threats.

"We will investigate this and charge anyone accordingly with the maximum charge we possibly could, for doing something so horrific, so pathetic," Israel said.

That same day, a grandmother in Washington state reported her grandson to police for allegedly planning a shooting at his high school.

Catherine O'Connor called police when she discovered her 18-year-old grandson’s journal as well as a semi-automatic rifle stored in a guitar case in her home, according to court records obtained by ABC affiliate KOMO in Seattle.

“What I’m reporting is I’m finding journal entries from my grandson,” O’Connor tells the 911 operator during the call, which was obtained by ABC News. “And he’s planning on having a mass shooting at one of the high schools.”

Police subsequently arrested the teen, who was a student at Aces Alternative High School in Everett.

Back in South Florida, there was a false alarm at North Broward Preparatory School in Coconut Creek regarding a report of shots fired Thursday morning. Students and faculty were evacuated as deputies searched the school, but the report was "unfounded," according to the Broward County Sheriff's Office.

Meanwhile, a juvenile was arrested in South Carolina on Thursday after posting an image to social media with a message saying, "Round 2 of Florida tomorrow." A version of the image, distributed by the Broward County Sheriff's Office in Florida, shows the unidentified suspect holding a firearm, with the individual's face blurred.

The Manatee County Sheriff's Office, on Florida's Gulf Coast, also confirmed that the image did not represent a "local threat" and was posted by a juvenile in Spartanburg, South Carolina.

ABC News' Courtney Han contributed to this report.