A 17-year-old boy from Westbrook was charged with terrorizing in connection with a social media threat that prompted officials to close two Portland high schools on Wednesday, police said.

The boy was issued a juvenile summons around 9 a.m. for threatening messages he directed at Casco Bay High School students on Snapchat, said Lt. Robert Martin of the Portland Police Department. Police have not identified the boy.

He said the messages included video and photos of what appeared to be a handgun. Police seized a BB gun Wednesday that they believe was featured in the post.

The incident comes as Martin said the police department has seen an increase in threats made by teenagers involving guns or BB guns. Similar threats, though not necessarily taking place in school, also have been reported in other communities, he said.

“Something has to be done about conflict resolution with these kids,” Martin said. “They are letting a sense of disrespect escalate into a deadly situation that in this case required the closing of a school, the disrupting of a whole bunch of people’s lives and an unsettled feeling, for nonsense.”

Officials of Portland Public Schools decided Tuesday to cancel classes at Casco Bay High School and the Portland Arts & Technology High School, which share a campus, because of the threat directed at about 20 Casco Bay students.

A student reported the threat Tuesday around 3 p.m. and dismissal occurred at the normal time without a need for a lockdown.

The threat also prompted a lockout at Westbrook High School and Regional Vocational Center on Wednesday morning, although there was no direct threat to those schools, police said. The Canal Elementary School also went into a lockout because of its proximity to the two Westbrook schools.

A lockout involves heightened security for entering and exiting the building and limits movement throughout the building.

Martin said Wednesday that he couldn’t provide further information about the group of students involved, but said the threat was made following a “long-standing dispute.” The student who made the threat did so in an attempt to intervene on behalf of a friend involved in the original dispute, Martin said.

Martin said police officers will be at Casco Bay and PATHS on Thursday to reassure students and staff. Both schools will be open as usual.

“We’ve addressed the threat and don’t think there is any ongoing threat to the community with this incident,” he said. “But we understand it will be tough going back and trying to re-establish a sense of calm and normalcy. That is what we will be striving for tomorrow.”

In a news release from Portland Public Schools, Casco Bay Principal Derek Pierce thanked the department for its work on the case.

“We are also grateful for all the support we have received from students and families in our school community and around Portland during this challenging day,” Pierce said. “We are excited to resume learning tomorrow.”

He said school counselors and support staff will be available for any students who need it Thursday. There will be a meeting at the school at 5:30 p.m. Thursday for any parents, students or community members who want to discuss the incident further, the school’s response to it or school safety generally.

Martin said parents should monitor their students’ activities and social media accounts and be aware that it is illegal to fire a BB gun in a public place in the city of Portland.

“There is no reason a 15- or 16-year-old should be leaving their house with a gun that looks like a real handgun,” he said. “The fear is they will use that to intimidate someone and someone’s going to respond – either a police officer or another person carrying a weapon – and perceive that as a threat and there will be a tragedy.”