A search and rescue mission was underway Monday morning for a submarine that went missing off the coast of southeast Canada on an expedition to explore the wreckage of the Titanic. Lt. Jordan Hart of the U.S. Coast Guard in Boston told CBS News that personnel were "currently undergoing a search and rescue operation" when asked about the rescue efforts off the coast of Newfoundland. It is not clear how many people are on board the missing vessel. OceanGate Expeditions, a company that deploys manned submersibles for deep sea expeditions, recently said on its website and social media feeds that...