* Three girls left Minnesota three weeks ago to join ISIS insurgents in Syria * Their identities have not yet been revealed * The FBI has subpoenaed a 19-year-old girl's family to appear before a Grand Jury later this month * She was about to start nursing classes at St. Paul College but decided to leave to give aid to wounded fighters * The girl is one of five children to a single mother originally from Somalia * She had recently started taking classes at al-Farook Youth and Family Center, an alleged recruiting ground for ISIS At least three young...