The accident happened around 2:00 a.m. along Route 206 in Lawrence Township, New Jersey.
According to officials, the bus was leaving the school after dropping off some students when it collided with a small vehicle.
Diaz was inside the car and was pronounced dead at the scene.
The school bus was from a company called First Student.
It's not clear if the bus driver suffered any injuries.
There is no word on what caused the crash.
The University is providing counselors for students who need their services.
They've asked the community to keep Eliseo's family in their prayers.