Exchange student arrested in Pennsylvania for allegedly 'threatening to shoot up' high school: Police The suspect, 18, had a military vest and ammunition at his home, police said.

An 18-year-old exchange student from Taiwan was arrested Tuesday night for allegedly "threatening to shoot up" a Pennsylvania high school, local police said this morning.

According to the Upper Darby Police, the suspect, An Tso Sun, had a slew of items in his home including: a military-style ballistic vest; high-powered crossbow with scope and light; arrows; 29 rounds of 9mm ammunition; a strangling device; a "military" ski mask; and ear protectors for firing.

Authorities also found a school-issued iPad that allegedly showed Sun was searching weapons like AK-47s and AR-15s, said Michael Chitwood, superintendent of Upper Darby Police.

Sun allegedly told a fellow student at Bonner Prendergast Catholic High School to “not come to school on May 1” because he “was going to shoot up the school," Chitwood said at a news conference today. Sun then allegedly told the classmate he was “kidding,” Chitwood said.

The classmate also said Sun asked how to purchase a gun, Chitwood said.

That student went to school officials, who notified Upper Darby Police, Chitwood said. It was not immediately clear if Sun had a lawyer.

Sun was charged with terrorist threats with the intent to terrorize another. He was arraigned Tuesday night and held without bail pending a psychological evaluation, authorities said.

The teen is on a student visa that was issued in July 2017 and expires in July 2022, authorities said today. Federal authorities have been contacted.

School spokesman Kenneth Gavin said in a statement, "Archdiocesan schools take the safety and security of every student, teacher, and staff member very seriously. Thankfully, no one was harmed. Incidents such as this demonstrate the importance of all members of the school community working together to maintain a safe environment."

"Parents have been asked to speak to their children and remind them that they should always report any suspicious activity immediately," Gavin said. "They have also been encouraged to contact police if they have information that will be helpful to the ongoing investigation."

The Archdiocesan schools "have been conducting a review of emergency protocols—fire, shelter-in-place, lock-down, etc.," Gavin said. "We will continue to monitor and review our protocols to ensure that our schools remain safe, healthy environments where young people can learn and grow."

The school is cooperating with the police investigation, Gavin added.