Mass shootings more common since 1960s

NEW YORK -- Mass public shootings have become such a part of American life in recent decades that the most dramatic of them can be evoked from the nation's collective memory in a word or two: Luby's. Jonesboro. Columbine.

And now, Virginia Tech.

Since Aug. 1, 1966, when Charles Whitman climbed a 27-story tower on the University of Texas campus and started picking people off, at least 100 Americans have gone on shooting sprees.

And all through those years, the same questions have been asked...