Findlay High School was placed on a Level 2 lockdown on Monday.
The school said the lockdown was initiated due to an incident involving a student, and that school officials and police responded quickly and the situation was resolved without harm to students or staff.
School officials said there was no gun involved in the incident.
Once authorities determined there was no ongoing threat the lockdown was lifted, a little after noon, and normal school operations resumed.
A Level 2 lockdown calls for all doors to be closed and locked and there are no class changes.