Students, staff and faculty evacuated Mentor High School after a bomb threat was found written on a bathroom wall at 12:51 p.m. Wednesday.
Specifically, the message insulted a unit principal in the building and said there would be an explosion at 1 p.m., Mentor Police Lt. Tim Allen said.
Police searched the school and, after finding the building was safe, allowed everyone back inside. The search took about 30 minutes.
The 16-year-old boy who is suspected of writing the threat is in police custody, according to the Mentor Schools web site.
The boy has been charged with making false alarms, criminal damaging and inducing panic.
When asked if there was any indication that the student intended to follow through on the threat, Mentor Schools spokeswoman Kristin Kirby said, "No."