CBS Evening News | Investigators say the student who opened fire last week at a Colorado high school was firing at random when he struck a 17-year-old girl in the head, putting her in a coma

Investigators say the student who opened fire last week at a Colorado high school was firing at random when he struck a 17-year-old girl in the head, putting her in a coma. The shooter's primary target was a librarian who had previously taken disciplinary action against him. Rick Sallinger of CBS station KCNC reports. Air Date: Dec 16, 2013