An empty shell casing was found in a school classroom in Braintree, Massachusetts on Thursday.
The principal of Granite Academy, Amy Barber, sent an email to parents Thursday night informing them of the discovery.
Barber said in the email the empty shell casing was found by a staff member at the end of the day, after students had been dismissed.
She said the finding was immediately brought to her attention and the school followed procedure by contacting Braintree police.
Braintree police and their K9 unit searched the entire school campus Thursday. As a precaution, there will be two plainclothes officers on campus Friday.
"I can assure you that our campus is clear and safe," Barber said in the email.
The head of school said they will continue to work closely with local police in following up on this incident, including having police speak with each staff member who was in the classroom where the shell casing was found.
They are also reaching out to meet with students who were in that classroom identified and their parents in person.
"I want to assure you that this is being taken incredibly seriously. I have the utmost confidence that our campus is safe for your child to return tomorrow," the email statement read. "Your child's safety and the safety of our staff team is my top priority."
Barber encouraged parents to reach out to her with any questions or concerns.
Granite Academy is a day school for middle and high school aged students, from grades 5-12, who have social/emotional challenges that complicate their learning.