UPPER DARBY, Pa. (CBS)—Police in Upper Darby are investigating after they say a student was found in possession of a gun on school grounds.

The discovery was made at Upper Darby High School Wednesday morning.

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The principal says they were informed of a rumor going around that a 12th grade student had a gun.

He says once the student got off the bus, he was confronted by officials. The principal says the student tried to hand off the gun to an 11th grade student, but it was intercepted by security.

Both students were brought into the school’s security office.

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Police say the loaded gun was found in a black box, along with marijuana. Police Superintendent Michael Chitwood says the gun was “loaded and ready to go.”

Chitwood adds the 12th grade student had previously gotten in trouble for allegedly threatening to kill Pope Francis when he was in Philadelphia in 2015.

“This kid should’ve been put away for evaluation, but now he’s walking in with a gun.”

Officials say the school does not have metal detectors.

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The students, both 17-years-old, are currently being charged as juveniles.