UPPER DARBY, PA (KYW/CNN) - A foreign exchange student stands accused of building an arsenal and planning to shoot up his Pennsylvania school.
An-Tsu Son, an 18-year-old foreign exchange student from Taiwan, was charged with making a terrorist threat to his high school, Monsignor Bonner Archbishop Prendergast Catholic High School.
The Upper Darby Police Department said Son told a friend not to come to school on May 1 because he was going to shoot up the school and then he said 'he was kidding.'
Investigators later discovered that Son used his school iPad to look up guns like an AK-47 and an AR-15.
"One of my teachers saw him getting walked out in handcuffs," said Brian Dunphy, a senior at the school. "He sat only a couple of rows over from me."
But Dunphy said it was Halloween when he noticed Son's behavior.
"He wore like a full military costume,” said Dunphy. “It looked pretty legit. He did have a fascination with guns, (and) people overheard him talking about guns and stuff."
“Everybody was surprised,” said another student, Mouloukou Sidibe. “They couldn't believe it.”
Officers showed evidence pulled from Son's bedroom: a military style ballistic vest, military web gear with pouches to hold ammunition clips and a high powered cross bow with seven arrows.
Police also found a bullet loading dock for an AR-15 and AK-47.
Police confirmed that Son’s host family is a female lawyer.
Her neighbors were shocked.
"If she were a future host, she might think twice now," said one neighbor.
"This is an active, open investigation, said Michael Chitwood of the Upper Darby Police Department. "There are a lot of questions that we need to answer."
Son underwent a mental evaluation and is now being held in the Delaware County Jail.
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