A 17-year-old student was arrested Tuesday morning at Long Beach Poly High School after campus officials found a loaded gun in his backpack, authorities said.

It’s not clear what the student was doing with the gun, but Poly High principal Bill Salas said yesterday that the campus remained safe during the incident.

School officials found the weapon after getting an anonymous tip that a student had brought a firearm on campus, according to Salas. Upon searching the student’s backpack, officials said, they found a gun and a campus security guard detained the boy.

When LBPD officers arrived at the high school around 9:36 a.m., they arrested the 17-year-old student on suspicion of being in possession of a firearm, department spokesperson Richard Mejia said. The boy’s name was not released by authorities because he is a minor.

“The involved student will face appropriate and significant disciplinary consequences,” principal Salas said. “Parents, please let this message serve as an additional opportunity to discuss the potential consequences of poor choices and long-term impacts on a student’s future.”

The firearm was seized at the scene, police said, and the investigation into the incident—including why the boy had the gun—is ongoing.

Millikan High School placed on lockdown after receiving threats, police say