The lockdown at Edmond North High School was lifted Wednesday morning when the bomb squad discovered a "suspicious package" was a lunch box.
The school was put on lockdown and students moved into the gym around 9:30 a.m. when someone found the lunch box tucked inside a cardboard box on the east side of the school near a culvert.
The Edmond Police Department's bomb squad X-rayed the package and discovered it was harmless.
The lockdown was lifted around 10:15 a.m., and students were allowed to return to class. Thomas Drive has also been reopened.