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PHILADELPHIA (CBS) – The teenager who authorities say plotted to shoot up a Delaware County school has been sentenced after entering an open guilty plea to terroristic threats on Monday.

Authorities say An Tso Sun, 18, of Taiwan, allegedly told a fellow student not come to school on a particular day because he was going to be shooting up Monsignor Bonner and Archbishop Prendergast High School in Drexel Hill.

Credit: (CBS3)

According to investigators, Sun stockpiled more than 1,600 rounds of ammunition and planned to shoot his fellow classmates on May 1.

“He was planning something horrible,” said Upper Darby Police Superintendent Michael Chitwood after his arrest in March.

Suspect In School Attack Plot Waives Right To Hearing In Exchange For Dropped Charge

On June 4, a judge sentenced Sun to four to 23 months in the George W. Hill Correctional Facility and to be paroled to the ICE detainer. He also was ordered to pay $700 in restitution, $350 each to Folcroft Police Department and Trainer Police Department for K-9 services.

The story has made international news as Sun’s parents are celebrities in Tawian. His father had a talk show and his mother is an actress.