A student was taken to hospital after an alleged incident involving a knife and several other students at Namadgi School on Wednesday.
An ACT Policing spokeswoman said officers arrived at the school in Kambah at about 1pm and ACT Ambulance Service took a student to The Canberra Hospital.
A patient transported from Namadgi School remained in hospital in a stable condition late on Thursday, an ACT Health spokeswoman said. At about 2pm on Friday afternoon, the spokeswoman said the patient had been discharged from hospital.
The ACT Education Directorate said the incident allegedly involved "a small number of students and a knife".
A spokesman for the directorate said all parents had been informed about what happened and students were commended for how they responded.
"A number of additional support measures are in place for students at the school and parents are encouraged to identify signs that their children may need additional support," the spokesman said.
He did not provide any more details about the severity of the student's injuries, where on the school grounds the incident occurred or how the knife was acquired.
One parent told Fairfax Media on Thursday that a student had stabbed another student at the senior school.
But neither ACT Policing or the Education Directorate would confirm this.
The education spokesman said the safety of staff and students was a top priority.
"All students in Canberra Public Schools have the right to be treated with fairness and dignity and to be in a safe and supportive environment – an environment that values diversity and an environment that is free from bullying, harassment, discrimination and violence.
"Deviation from these principles is taken seriously."
While the matter is now with police, the ACT Policing spokeswoman did not say whether parents at the school should be concerned for their childrens' safety.
They said investigations were ongoing.
The incident comes a week after Namadgi School allegedly suffered up to $25,000 worth of theft and vandalism.
Police said several rooms were broken into and items stolen included iPads and laptop computers in that incident.
Know more? Email clare.sibthorpe@fairfaxmedia.com.au