Investigators warning about 'unconventional violence'

In the wake of Monday's attack on the Ohio State University campus, investigators are talking about what they call "unconventional tactics" to commit violence.Police said when the suspect's car crashed into a crowd of unsuspecting people, 911 callers reported they heard a blast or a gunshot. Columbus Police Lieutenant Brent Mull said the moment of impact sparked the confusion.
"You're going to hear an explosion. If you don't see it, you hear what you think is an explosion,"said Mull.
For hours,