What may have led to “catastrophic implosion” of Titanic sub?

The Coast Guard confirmed Thursday they’d found debris that indicated the missing sub that was exploring the wreck of the Titanic had suffered a “catastrophic implosion,” killing all five on board. Stefano Brizzolara, an ocean engineering expert and co-director of the Virginia Tech Center for Marine Autonomy and Robotics, joined CBS News to talk about what may have caused the implosion. Source