Students and staff were evacuated from Mercer Island High School just before dismissal on Dec. 14 due to a bomb threat at the school.

The high school was closed and the building was cleared, according to Craig Degginger, communications and alumni relations coordinator for the Mercer Island School District.

The district worked with the Mercer Island Police Department (MIPD) to investigate the situation, according to its website. All after-school activities and athletics for that day were canceled.

The threat was written on a piece of paper found in an occupied classroom at the school, said MIPD Services Commander Jeff Magnan. The teacher immediately reported it to the administration, and MIPD was notified. Most students were sent home. Officers searched the school and interviewed some students, Magnan said.

The other schools in the district were not impacted and continued with the normal school day. All indications are that other private academic institutions on the Island were not involved, according to police.

The MIPD said it would provide follow-up information on its investigation on social media when available.

In an update on Thursday evening, Mercer Island Superintendent Donna Colosky wrote that “the threat [was] found not to be credible,” and that two similar incidents had occurred at the high school recently.

“In light of the three separate student-initiated threats at MIHS in the past few weeks, the Mercer Island School District is cancelling high school classes and all after-school and athletic activities at MIHS for Friday (Dec. 15),” she wrote. “All other Mercer Island schools will operate on regular schedule Friday, which is the last day before winter break. High School students are expected to respect the learning environments of the other schools and are not permitted to be on any school campus tomorrow. Although there is not a viable safety concern for tomorrow, taking this step allows MIHS students and staff to regroup.”

The students involved in Thursday’s incident have been identified, and the MIPD is working with the district and the students’ families, she wrote.

The district and MIHS administration said they would use the time off to collaborate with staff on ways to address these situations, and strategize on how to educate students on the “legal implications and extreme disruption these threats cause.”

“Our goal is to help maintain a positive high school community when school resumes January 2, 2018,” Colosky wrote.