Ian Pannell reports on the deadly Christmas market attack in Germany, after a car plowed into families, killing at least two people and injuring dozens more, with officials treating it as a deliberate act of terror; Stephanie Ramos has details on the powerful winter storm that's creating dangerous travel conditions from the Midwest to the Northeast as millions travel for the holidays, and Lee Goldberg has the forecast; Jon Karl has late reporting on the urgent push to avoid a government shutdown that could impact millions of federal workers; and more on tonight's broadcast of World News Tonight with David Muir.