San Diego mosque shooter Cain Clark's disturbing suicide note revealed, as 17-year-old's shellshocked GRANDPARENTS apologize for massacre that murdered three

A shooter, identified as Cain Clark, attacked a San Diego mosque, killing three people, and later took his own life, leaving behind a disturbing suicide note. The 17-year-old's grandparents have apologized for the massacre. The attack has left the community in shock.