A teenage boy was struck and killed by a train while walking along a SEPTA commuter rail line track in Middletown on Friday. Police identify the youth as 15-year-old Chris Mongillo of West Highland Avenue in Middletown. He was a student at Neshaminy High School. Investigators say the boy left a note at home. The Bucks County Coroner is calling the death a suicide. It happened on the same SEPTA track where another Neshaminy High School student was struck and killed by a train on New Year's Day.