Sixth grader killed, five others injured at school shooting in Perry, Iowa; U.S. airstrike kills leader of Iranian-backed militia in Baghdad; Newly unsealed documents reveal Jeffrey Epstein's relationships with powerful people; and more on tonight's broadcast.

Piece of Alaska Airlines plane detaches mid-flight, prompting emergency landing; First winter storm of new year moves through Northeast; U.S. official: Pentagon waited days to inform W.H. officials of defense secretary's hospitalization; and more on tonight's broadcast.