"The school was placed in lockdown as a result of high school administration being alerted that a student on campus was in possession of a firearm," the district said in a statement.
Suspects are in custody and police are investigating, the district said.
The view from Chopper 6 HD showed several police cars parked outside of the building.
"Everyone is safe," the district said in a statement. "We understand that lockdowns can be a very emotional situation for everyone involved, but the safety of our students and staff is always paramount."
The lockdown was lifted around 3 p.m.