A mentally challenged 15-year-old girl was gang-raped beneath her desk during class — only feet away from her teachers — at an Elmont, N.Y., school, according to a lawsuit filed Friday. When the girl reported the horrific incident the next day, school officials failed to report it, the victim’s mother claimed in the suit. The special-needs teen, known by the initials K.J., was allegedly sexually assaulted for 10 minutes under her desk by two teenage boys, as another “hit her on the head whenever she tried to escape,” during science class at Martin De Porres Academy, claims the lawsuit