In a press briefing on Thursday afternoon, US Coast Guard Rear Admiral John Mauger said a remotely operated vehicle (ROV) discovered the tail cone of the Titan submersible about half a kilometre from the bow of the Titanic on the sea floor.
"The ROV subsequently found additional debris. In consultation with experts from within the unified command, the debris is consistent with the catastrophic loss of the pressure chamber," Mauger added.
"I offer my deepest condolences to the families," he said.
The five passengers are Hamish Harding, a billionaire and explorer; Paul-Henry Nargeolet, a French explorer; Shahzada Dawood and his son, Suleman Dawood, members of a prominent Pakistani family; and OceanGate Expeditions CEO and Titan pilot Stockton Rush.
The submersible went missing more than 600 kilometre off the coast of Newfoundland in eastern Canada early on Sunday morning during a dive to the wreck of the Titanic in the North Atlantic, Xinhua news agency reported.
An international search effort led by the US Coast Guard had been racing against the clock to locate the missing submersible which was estimated to have a 96-hour supply of oxygen and its air supply was expected to run out on Thursday morning.
There were reports saying that the underwater sonar devices picked up banging noises on Tuesday and Wednesday in the area where the submersible vanished.
Mauger said there didn't appear to be any connection between the noises and the location of the submersible on the seafloor.
OceanGate Expeditions used the five-person submersible to reach the wreckage 3,800 metre below the ocean surface.
On its website, the company advertises a seven-night voyage to the Titanic for $250,000 per person with the money raised by tourists going towards Titanic research.
