Portland High School and schools in the Buxton area that closed Thursday following social media threats were planning to reopen Friday, officials said.

“Like we always are every day, we will be vigilant and mindful of school security and safety tomorrow but we will definitely be opening for school,” said School Administrative District 6 Superintendent Paul Penna.

All schools in SAD 6, which serves the communities of Buxton, Hollis, Limington, Standish and Frye Island, were closed Thursday because of a threat that surfaced on the social media platform Snapchat.

The threat included a photograph of handwriting on a wall that described an act of violence set to take place Thursday, according to the Cumberland County Sheriff’s Office. Administrators at Bonny Eagle High School were made aware of the post Wednesday, but the sheriff’s office said it could confirm that the threat originated at Bonny Eagle. It also did not target a specific school or school district and police said they did not believe the threat was credible.

An investigation is ongoing and there was no new information available Thursday, the sheriff’s office said.

Portland High School closed for a similar social media threat Thursday and students spent the day learning remotely. The school was to reopen Friday, said Tess Nacelewicz, communications coordinator for Portland Public Schools. David Singer, a spokesman for the Portland Police Department, said the agency had no additional information on the threat Thursday but there was no indication it originated in Portland.

Old Town High School also closed Thursday because of what the school described as “a threat to the safety of our students and staff,” but the superintendent said it did not appear to be linked to the threats in the southern part of the state.

The threat in Old Town was not made via social media and an investigation and search for the perpetrator are ongoing, Regional School Unit 34 Superintendent David Walker said in an email. He said the missed day of classes will be made up in the same manner as a weather-related cancellation and regular classes were to resume Friday.