The Ocean County Prosecutor’s Office has filed terrorism charges against a 19-year-old man accused of plotting to attack his high school graduation ceremony.

Matthew Vanderbeek was already facing charges of terroristic threats with an intent to kill and attempting to possess a firearm for an unlawful purpose.

The terrorism charges were added after receiving authorization from New Jersey Attorney General Gurbir Grewal, according to the prosecutor. Terrorism charges carry the potential of up to 30 years to life in prison if convicted.

Authorities say that Vanderbeek told several classmates that he intended to shoot students and staff at New Egypt High School’s graduation ceremony last week. He supposedly also made several posts on Snapchat that referenced potential threats. Students and teachers saw these posts and alerted officials.

Vanderbeek also enlisted the help of a friend to drive him to a gun shop to purchase a weapon, according to a police affidavit. That friend threw Vanderbeek out of his car once he heard what the teen was planning, according to police.

Vanderbeek is being held at the Ocean County Jail. A detention hearing is scheduled for Thursday.