Schools in three Massachusetts communities received threats, resulting in classes or activities being canceled on Thursday or an increased police presence on campus.
The threats were either received by officials or found on campus on the following campuses: Phillips Andover in Andover; Curtis Middle School in Sudbury; and Algonquin Regional High School in Northborough.
Thursday's classes were canceled at Phillips Andover after a dean received a threat via email the day before, but school officials said there was nothing specific in the threat to the Andover campus, and authorities are not sure if the email may have been meant for a school in New Hampshire.
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In Sudbury, police officers were on campus as Curtis Middle School students arrived after school officials received a report of a potential threat by a student involving a firearm.
In a Facebook post, Sudbury police said they were immediately notified of the threat and communication began with families.
"Parents were cooperative allowing us the opportunity to verify there was no access to any firearm. Given the progress of the investigation at this point, we are confident no threat exists involving said investigation," police said.
Meanwhile, a police investigation is underway after a threatening note was found Wednesday afternoon in a bathroom stall at Algonquin Regional High School in Northborough.
Police said the note was specific to Thursday but did not reference any particular school or students. They believe the threat was directed at Algonquin Regional High School.
Due to the threat, school officials will have an increased police presence on campus Thursday and have postponed graduation rehearsal until Friday.
The school threats remain under investigation.