TAIPEI, Taiwan (AP) — People who know the 18-year-old Taiwanese exchange student charged in the U.S. with threatening to shoot up his school say he liked guns and flamethrowers and also had dreams of a police career.

An Tso Sun, who has been jailed in the state of Pennsylvania, was "a child who really cares about things," said Cheng Chu-yi, who home-schooled Sun in Taiwan's capital, Taipei.

"He was an extremely simple and kind student, yet he would often have unusual ideas," Cheng said.

Police in Upper Darby, Pennsylvania, say Sun threatened to commit a shooting at Monsignor Bonner and Archbishop Prendergast High School.

Deadly school shootings in the United States have triggered some of the biggest youth protests in recent years and calls for stronger gun control measures.