The lockdown at Central Dauphin East High School was lifted at 11:30 a.m., according to district spokeswoman Shannon Leib.
Classes have resumed and the school operating as normal according to Leib, but "District administration notified local law enforcement who are currently at the school investigating the incident."
The number of students involved and any injuries were not released.
Click here to follow Daily Voice Gettysburg and receive free news updates.