Principal James Riccobono addressed the 2,900 students before classes began Monday. The principal praised a student for alerting authorities.
Two students were arrested after authorities seized guns, ammunition and explosives, allegedly meant to be used in an attack on the school.
Authorities swept Bridgewater-Raritan sometime prior to the start of classes as a safety precaution.
Teachers say they are ready to help any struggling students or those who might have information about the case.
Police say the plot came to light when another student told police that a 16-year-old junior had spoken about his plan to attack the school and students.
Police arrested the teen, who allegedly had shotgun shells, black powder and improvised explosive devices.
Then, a 17-year-old Immaculata High School senior was also arrested. Police say he is a competitive rifle shooter and allegedly had rifles, shotguns and shotgun shells.
Police say the teens also obtained PVC piping, wiring, light sockets and bulbs at a Home Depot to make their bombs.
Police won't name either suspect because both are minors.
The 17-year-old faces third-degree charges of possession of destructive devices.
The 16-year-old faces more serious charges, including attempted murder, possession of explosives, possession of a destructive device and attempted widespread damage or injury.