Three recent weapons-related incidents in the Cumberland-area school district didn’t involve guns on campus but were serious enough that police were either notified or involved, the superintendent said Thursday.

“Was there a gun on the school campus or that made its way on to the school campus in any of these three instances? The answer is definitively no,” School Administrative District 51 Superintendent Jeff Porter said in a 10-minute video message to the community the day after he sent parents a letter informing them of the incidents over the past week.

One incident involved a threat. Two others involved threats and students bringing weapons to campus, Porter said in an interview.

In Porter’s Wednesday letter to parents in the district, which also includes North Yarmouth, he asked them to remind their children not to bring “inappropriate” items to school and to seek out school staff if they feel frustrated or worried.

The incidents happened at a time of heightened tensions around school safety following a school shooting in Michigan last week that killed four students and injured several others. They also highlight the difficult choices school administrators face when responding to and communicating with the community about threats of school violence.

“I think there’s this feeling that any time there’s some sort of a dangerous behavior we’re immediately going to go notify the school community about it,” Porter said. “That’s where the confidentiality comes in. It’s a hard balancing act schools must play, and I had to be really careful about the messaging and how much I was going to message. I know that’s frustrating and it can be difficult for people to understand because human nature is they want more detail.”

Porter would not say what weapons were involved in the three unrelated incidents or whether any of them were racially motivated.

All three incidents were targeted threats against other students in SAD 51, which Porter said played into his decision not to make immediate announcements about them. There is no written policy in the district about when a communication should be sent. But Porter said that as a general rule he would not send a mass communication about a targeted or isolated threat, as he would about a general or school-wide threat.

“It was the cumulative nature of these three within a short period of time that made the difference,” he said.

Porter said he could not say whether specific disciplinary action was taken against the students involved, but in his video message he said they were “held accountable.”

In general, a student bringing a weapon to campus would be suspended from school, at minimum. The typical discipline for a student who makes a threat varies, depending on such factors as the age of the student and whether the threat is targeted or general. Porter said he was not aware that police had charged anyone in the three incidents.

Cumberland Police Chief Charles Rumsey did not respond to email and voice messages about the incidents Thursday.

Jessie Butler, whose son is in fourth grade at Greely Middle School, was frustrated by Porter’s letter Wednesday and said there should have been more communication.

“The first thing that came to my mind was, ‘What are you talking about?’ ” said Butler, who lives in North Yarmouth. “This is the first time we’re hearing about it and there have been several incidents?”

At a minimum, Butler said, parents in the sixth- through eighth-grade area of the middle school should have been notified sooner.

“If those grades were notified prior to (Wednesday), then that should have been put in that letter because we don’t know,” she said. “You read that letter and it just seems like, ‘Wait, does that pertain to me and my kid?’ It was just confusing.”

Kate Perrin, who has three children in the district, two at the middle school, said she is confident in the district’s response and communications, but worries about support for the students involved.

“Any parent that assumes their children’s schools are immune from the pervasive culture of violence and the untreated mental health struggles of teens is perhaps not paying attention,” Perrin said in an email.

Porter said the district has protocols in place for responding to school safety incidents but is also making updates. The district has a a full-time school resource officer who works in all the district’s schools, Porter said, and staff, including teachers, social workers, school counselors and a mental health risk assessment coordinator, also are involved in safety, mental health assessment and support.

Still, he said, the district is seeing an increase in “worrisome behavior” from some students that may be at least partially related to the COVID-19 pandemic.

“Over the last three years, I think kids have had broken schooling, broken relationships and everything has sort of been on pause,” Porter said. “Now they’re expected to come back to school and participate in everything they were before. For most kids that’s really exciting and they want to move on. For some students it’s really overwhelming, and there are also circumstances with parents being out of work and family situations.”

Porter said the district is increasing its efforts to identify students in need of extra support, and to work on social and emotional learning.

“That’s one of our big focus areas,” Porter said. “Staff are more aware of (the challenges students are facing) and are implementing those things and, quite frankly, I think even students themselves are more aware of anything out of the ordinary and are reporting it.”