Fryeburg Academy has ended its lockdown and resumed normal classes.

The school was placed in lockdown mode late Thursday morning to investigate a handwritten threat of a gun on a bathroom stall that was reported by a student, according to a release from the Fryeburg Police Department. The school reported on its social media accounts that a security issue was being investigated.

“We are investigating a security issue, classes are continuing, and we will update you soon,” read a post on the school’s Facebook page.

Phone calls to the school’s office were not answered.

The private boarding and day school in Fryeburg enrolls about 400 high school students.

The school announced on its Twitter page at 12:20 p.m. that the lockdown was over. The school continued its normal school activities after authorities determined that the threat was not credible.

Fryeburg Police were assisted by Maine State Police, Conway Police, Fryeburg Fire, and Fryeburg Rescue, which closed nearby streets while the incident was investigated.