Police in Upper Darby, Pennsylvania, say that a foreign exchange student at a Philadelphia-area high school may have been planning a mass shooting.
18-year-old An Tso Sun had a stash of 663 rounds of 9 millimeter ammunition for a handgun he built himself; 295 rounds of AR-15 rifle ammunition and 425 rounds for an AK-47. His plan reportedly may have been targeted for May 1st. Sun had reportedly warned a female student not to come to school that day.
Police are also investigating to see if any other people were involved with the plot. Sun has been arrested for making terroristic threats.