The submersible that went missing during a tourist expedition to the Titanic imploded near the wreckage, killing all five people aboard, US Coast Guard officials announced Thursday, bringing a grim end to a massive international search for the vessel.

Five crew members onboard the submersible Titan that went missing during a tourist expedition to the Titanic were probably killed instantly in a “catastrophic implosion” as the vessel descended to the Titanic shipwreck two miles below the surface of the Atlantic Ocean, the US Coast Guard announced Thursday.

A large debris field containing multiple sections of the submersible was spotted earlier in the day by a remotely operated vehicle scouring the seabed near the Titanic wreck site, officials said at a news conference in Boston. The sub is believed to have imploded in the water, causing debris to land several hundred meters from the Titanic site.

“The debris is consistent with the catastrophic loss of the pressure chamber,” said Rear Adm. John Mauger, the head of the search-and-rescue operation. “We immediately notified the family on behalf of the US Coast Guard and the entire unified command. I offer my deepest condolences to the families. I can only imagine what this has been like for them.”

The announcement brings a grim end to a massive international air and sea search for the sub and its crew. The 22ft (6.7m) vessel went missing Sunday, one hour and 45 minutes into its scheduled 11-hour dive. Its 96-hour oxygen supply would have run out Thursday morning.

During the initial hours of the search, a Navy analysis of acoustics in the water found an “anomaly” consistent with an implosion or explosion in the approximate place and time that the sub lost contact with its Canadian-owned parent ship.

US defence officials said Thursday top secret underwater microphones had detected sounds “consistent with an implosion” shortly after the submersible disappeared and that this information was immediately shared with the US Coast Guard to assist with the search.

“I know there’s a lot of questions about why, how, when this happened,” Mauger told reporters. This is an incredibly difficult and dangerous environment to work in out there, but those questions … are going to be the focus of future review.”

The Coast Guard official, who was unable to say if attempts would be made to recover the bodies, said it was too early to tell exactly when the catastrophic implosion occurred.

The Coast Guard’s announcement came just minutes after OceanGate Expeditions, the company that owned the submersible and operates dives to the Titanic, issued a statement saying its pilot and CEO Stockton Rush, along with passengers Shahzada Dawood and his son Suleman Dawood, Hamish Harding, and Paul-Henri Nargeolet “have sadly been lost”.

“These men were true explorers who shared a distinct spirit of adventure, and a deep passion for exploring and protecting the world’s oceans,” it said in a statement. “Our hearts are with these five souls and every member of their families during this tragic time.”

The Titanic hit an iceberg and sank in 1912 during its maiden voyage from England to New York with 2,224 passengers and crew on board. More than 1,500 people died. The ship was found in 1985 and remains a lure for nautical experts and underwater tourists.