Dr. Phillips High School was placed on lockdown just before noon Wednesday.
According to school officials, a student reported seeing a gun.
Police responded and after a search, nothing was found.
The Lockdown was lifted around 12:40pm.
OPD officers said they would remain on scene with an increased presence past an early dismissal time of 1:15 pm.
Investigators said they are searching for a possible weapon.
The circumstances surrounding the incident have not been released.
No other details are available.