Updated at 10:15 p.m. Thursday: Revised to include a fifth incident.

Three North Texas high school students — one each at Marcus High in Flower Mound, Plano West and South Garland — were arrested Thursday after reportedly taking guns to their campuses a day after the deadly shooting in Florida.

The Marcus High and South Garland students each face a charge of carrying a firearm in a prohibited place. The Plano West student also may face a felony charge.

The weapons were not fired, and there were no injuries at the schools.

Also Thursday, an Arlington junior high student was arrested after allegedly making threats to shoot the school, and a Weatherford teen was arrested after making vague threats on social media, police said.

Neither student had a weapon, police said.

Marcus High

School resource officers at Marcus High arrested a 16-year-old, who was not identified, after other students reported that the student had a firearm, police said.

Officers found an unloaded, small-caliber handgun and ammunition after removing the student from a classroom. The student was taken into police custody.

Police "do not believe the student intended to harm anyone on campus," Marcus principal Gary Shafferman told parents in a letter.

South Garland

At South Garland, a school resource officer and the principal confronted 19-year-old Kerry Guery about noon after another student reported that Guery had stolen a cellphone. The phone, an unloaded handgun and marijuana were discovered in Guery's backpack, Garland police Lt. Pedro Barineau said.

Kerry Guery

In addition to the gun charge, Guery was charged with possession of marijuana in a drug-free zone and tampering with an identification number because the gun's serial number had been scraped off, Barineau said.

He also had two theft warrants out of Dallas County.

Police do not know whether Guery intended to the use the gun, and no ammunition was found.

"Obviously, we’re very cautious in regards to any type of behavior that could lead us to believe some sort of violence could occur," Barineau said.

Plano West

At Plano West, a school resource officer took a juvenile with a handgun into custody while investigating a Campus Crime Stoppers lead, Plano police spokesman David Tilley said. The tip indicated that a student had brought a handgun to campus.

Reports of students bringing guns to campus are not common in the Garland or Plano ISDs, but Thursday's incident underscores the benefits of having the Crime Stoppers program and on-campus resource officers who are in a position to respond quickly, Tilley said.

"The students can make these reports and potentially ... save a major incident from taking place," he said.

Campus Crime Stoppers operates under the umbrella of the Crime Stoppers program and with the North Texas Crime Commission and has a presence at 142 campuses across North Texas, according to the commission's website.

Like the Crime Stoppers program, students can receive cash rewards for tips.

The North Texas arrests came one day after a young man who had been expelled from Marjory Stoneman Douglas High School walked onto the South Florida campus and killed 17 people.

"It’s disturbing regardless of what happened yesterday or any other time; it’s always disturbing when a kid brings a gun to school," Tilley said. "You really never know what their motive behind doing that is."

No reported threats had been made by the Plano student Thursday or before that. It wasn't clear what charge he would face or where he got the gun, which was confiscated, Tilley said.

It is a felony to possess a gun in a weapon-free zone such as a high school campus, and Tilley said it's not something that's taken lightly.

"I don’t quite understand it, especially in the climate we’re facing today," he said. "It’s a disturbing trend that is taking place, and if these kids think that it’s funny to bring a gun to school even if they have no intent of using it ... they’re finding out it’s not that funny."

Nichols Junior High

At Nichols Junior High, a 13-year-old was arrested Thursday after other students reported that he had made threats to shoot up the school, Arlington police said.

No gun was found, but "based upon the fear it caused," the student was charged with terroristic threat, police Lt. Christopher Cook said.

Cook said that police take all threats seriously but that situations such as Thursday's are not common.

The student reportedly had talked about bringing an AK-47 to go after people, KDFW-TV (Channel 4) reported. Police told the station that the student denied having a gun and said he had been joking about bringing a toy gun that shoots foam bullets to school.

Weatherford High

A 16-year-old student was also taken into custody Thursday at Weatherford High School after allegedly making "vague" threats on social media, which alarmed other students, Weatherford Deputy Chief Chris Crawford said.

The student, who hadn't been identified, was taken into custody by a school resource officer and transferred to a juvenile detention facility. She has been charged with terroristic threat.

No weapon was found and nothing led law officers to think she was an immediate threat, Crawford said.

"What we're seeing more and more of is that students and young adults are posting things on social media and kids don't realize ... their words have consequences nowadays," he said.

Crawford said he thinks students are becoming too comfortable with social media and don't understand that their posts can reach a far wider audience than they expected.

"With the national threat that's out there today ... it scares parents, and they have every right to be scared, and it scares students," he said. "It's a legitimate feeling of uneasiness when you have a fellow student that's posting something or writing something that others deem as threatening. No students or staff should have to live in fear."

School shootings

In January, the Italy High School cafeteria was the scene of a campus shooting. A 16-year-old boy is accused of opening fire at the Ellis County school, striking 15-year-old classmate Noelle Jones six times and narrowly missing a male student. Noelle is expected to recover.

The gun control advocacy group Everytown for Gun Safety has pushed a claim that there have been 18 school shootings this year.

A Washington Post review of the data, which included a suicide outside a closed Michigan elementary school, found that only five of the shootings happened during school hours and resulted in physical injury.

Three others appeared intentional but hurt no one, and two more involved guns carried by school police or licensed peace officers that were unintentionally fired.

Staff writer Sarah Sarder contributed to this report.