Portland High School and all schools in the Bonny Eagle district will be closed Thursday after threats of violence were made on social media and shared by students.

While school and law enforcement officials don’t believe the threats shared on the social media platform SnapChat are credible, the schools are being closed “out of an abundance of caution.”

The social media threats are part of a problem that has plagued school districts across the United States for several years.

The short video shared among Bonny Eagle students showed an unidentified person writing on a whiteboard, “I will shoot up the school Thursday, September 30th,” said Paul Penna, superintendent of School Administrative District 6.

“This isn’t something we’re going to play games with,” Penna said.

Cumberland County Sheriff’s Capt. Donald Foss said classes are canceled Thursday in all schools in SAD 6, which serves the towns of Buxton, Hollis, Limington, Standish and Frye Island.

“The handwritten message did NOT target a specific school or school district and could not be confirmed to have originated at Bonny Eagle High School,” Foss said in a written statement Wednesday night.

“At this time, Bonny Eagle school officials and law enforcement do not believe this threat is credible, nor do we believe the threat was written on any schools within the Bonny Eagle School District,” Foss said. “School officials and law enforcement continue to work closely on this case to determine the origin of the message.”

Foss said all school buildings and grounds in SAD 6 were searched and the “original threat” was not located.

Based on a similar threat, Portland High School students will learn remotely Thursday, while in-school classes will be held as usual in all of the city’s other schools, including Deering High School, Casco Bay High School and Portland Arts and Technology High School.

“Other public schools in Portland are not considered at risk and will be open as usual tomorrow,” said Tess Nacelewicz, communications coordinator, in a written statement. “We are grateful to the Portland Police Department for their timely help in assessing the threat and continuing to monitor the situation to ensure student, staff and community safety when we return to school on Friday.”

While Portland police also have determined the threat does not appear to be credible, all after-school activities are canceled Thursday in Portland schools.

Old Town High School also canceled school on Thursday “due to a threat to the safety of our students and staff,” according to a post on the school’s Facebook page Wednesday night. The post didn’t say how the threat was made. “The lost day will be added to the school calendar and made up at a later date,” the post said.

Shannon Moss, spokesperson for the Maine Department of Public Safety, said Wednesday night that Maine State Police had received no reports of similar threats to other schools in Maine.

Similar social media threats have resulted in school closings, lockdowns and student arrests across the country in recent years, including Arizona, Florida, Tennessee and Minnesota.

Penna expressed frustration over the incident in his district.

“Social media is just killing our society,” Penna said. “It makes people live on this edge for no good reason. There is nothing to be gained from doing this.”