The three Hempfield Area High School students caught selling and buying guns Monday are facing felony charges.
Troopers say both of the weapons were stolen.
The 15-year-old boys are being charged as juveniles with carrying firearms without a license, receiving stolen property and causing or risking a catastrophe.
State Police say one of the students involved allegedly threatened another student in class, but didn't display the gun.
He's charged with terroristic threats.