Human remains were likely recovered from the Titan submersible wreckage, the U.S. Coast Guard announced Wednesday night, nearly a week after five people aboard the submersible were presumed dead after a “catastrophic implosion.”

The remains were “carefully recovered within the wreckage at the site of the incident,” the Coast Guard said in a news release, adding that U.S. medical professionals will “conduct a formal analysis of presumed human remains.”

“The evidence will provide investigators from several international jurisdictions with critical insights into the cause of this tragedy,” Marine Board of Investigation Chair Captain Jason Neubauer said in a statement. “There is still a substantial amount of work to be done to understand the factors that led to the catastrophic loss of the TITAN and help ensure a similar tragedy does not occur again.”

The announcement came as debris from the destroyed vessel returned to land Wednesday at a Canadian coast guard pier. Photos from the wharf in St. John’s, Newfoundland, show what appeared to be several pieces and twisted chunks of the submersible.

The debris will be further analyzed and tested as part of the ongoing investigation into why the implosion occurred. The investigation, involving several government agencies from the United States and Canada, is being led by the Coast Guard.

Search and rescue teams had found debris on the sea floor about 1,600 feet from the bow of the Titanic on June 22, four days after it went missing.

Coast Guard officials said the debris was “consistent with catastrophic loss of the pressure chamber” in the submersible. The five passengers were believed to be dead, according to OceanGate, the company that led the tourist mission and operated the vessel.

US Coast Guard leads Titan investigation

On Sunday, the Coast Guard announced it was leading the investigation into the loss of the submersible to determine what caused the implosion.

Salvage operations started on the ocean floor and the Canadian-flagged Horizon Arctic carried a remotely operated vehicle (ROV) that searched the area of the wreckage site, about 435 miles south of Newfoundland.

The company that owns the ROV, U.S.-based Pelagic Research Services, confirmed Wednesday that its team “successfully completed” offshore operations and was now removing its equipment from the Horizon Arctic after “working around the clock for 10 days.”

PATENTS, LAWSUITS, SAFETY CONCERNS:A timeline of OceanGate’s Titan sub.

‘Major marine casualty’

The Coast Guard and National Transportation Safety Board called the incident a “major marine casualty.”

The five passengers who were aboard the submersible when it imploded were OceanGate’s CEO Stockton Rush; British billionaire explorer Hamish Harding; French maritime and Titanic expert Paul-Henry Nargeolet; one of the richest men in Pakistan Shahzada Dawood and his son Suleman Dawood. 

It was OceanGate’s third annual expedition to the Titanic, where the company offered extreme tourists a chance to become one of the few to “see the Titanic with your own eyes,” according to an archived itinerary of the mission. Each passenger had paid $250,000 to see the wreckage.

The vessel, criticized for its unconventional design, was made of carbon fiber and titanium. It was about 9 feet high, 8 feet wide, 22 feet long, and weighed 25,000 pounds, according to OceanGate.

The Titan had imploded on its journey to tour the Titanic wreckage and debris was found at about 12,500 feet — where there is enormous pressure, absolute darkness and extremely cold temperatures. Last week, authorities found “five major” parts of the vessel, including its tail cone and landing frame.

The Marine Board of Investigation said Wednesday it will continue evidence collection and witness interviews “to inform a public hearing regarding this tragedy.”

Contributing: Camille Fine and Kayla Jimenez, USA TODAY; Associated Press