Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

In the days following the mass shooting at a Parkland, Florida, high school that killed 17, several teens who purportedly shared similar sentiments across the country have been arrested for threatening their schools.

On Thursday, Vermont State Police said they had arrested Jack Sawyer, 18, and charged him with attempted aggravated murder, attempted first-degree murder and attempted aggravated assault with a deadly weapon for allegedly expressing "his desire to cause mass casualties at the Fair Haven High School."

14-year-old arrested for allegedly threatening to 'shoot up' Port St. Lucie school Port St Lucie Police Department

During a press conference on Friday, police said Sawyer had been released from a mental institution a few days ago, and he soon after purchased a shotgun. According to police, Sawyer’s plans were not inspired by the Parkland shooting.

Vermont Gov. Phil Scott, a Republican, said "everything should be on the table" as legislation is considered, noting that the dialogue should not only center around gun control.

Then on Friday, New York Gov. Andrew Cuomo said two schools in Upstate New York appeared to experience "copycat" threats from unidentified individuals.

Related: FBI got tip on alleged Florida shooter Nikolas Cruz in January, but didn’t ‘follow protocols’

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

"These two matters are under control," Cuomo said in a statement. "The schools involved were the Chautauqua Lake School District and the Randolph Academy in Cattaraugus County. Both students are in police custody. State Police are on site, and the schools are functioning once again after a brief closure this morning."

Cuomo said that in the days after a tragic incident like the one that occurred in Parkland, "we must take a firm stand against any ‘copycat’ actors."

Also on Friday, in Port St. Lucie, Florida — little more than an hour north of Parkland — a 14-year-old was taken into custody after he allegedly threatened to "shoot up" a middle school.

NBC News is not naming the boy because police are not charging him as an adult.

While messaging on Instagram, the boy told a friend he had been suspended for 10 days from Southport Middle School in Port St. Lucie, and added that he might be expelled, police said.

"I hope I do [get expelled] so I can shoot up the school," the boy wrote in the message, according to an arrest report.

A girl who saw the messages told her parents, who contacted police, the arrest report said. Police then charged the boy with a felony count of intimidation.

Related: Day before Parkland, grandmother foiled grandson’s alleged school shooting plans

According to the arrest report, the mother told police that her son owned a BB gun.

In Middletown, Ohio, NBC News affiliate WLWT reported that police arrested a student after his threat led to Middletown High School to go on lockdown.

"People were confused and a lot of people were scared," ninth-grader Trey Angelini told WLWT. "There was a couple people crying in there, because they thought they were going to get shot or something."

Later on Friday, NBC News affiliate WMC in Memphis reported that a 17-year-old had been arrested by Memphis Police after he threatened Northwest Prep Academy on Facebook.

According to WMC, police said they charged the boy with commission of an act of terrorism.