The company behind the missing Titan submersible said all of the five people on board the vessel are believed to be dead, the US Coast Guard said on Thursday.

Earlier, the US Coast Guard said that rescuers uncovered a “debris field” within the search area where teams are searching for the missing Titan submersible that was traveling to the wreck of the Titanic.

“A debris field was discovered within the search area by an ROV near the Titanic. Experts within the unified command are evaluating the information,” the US Coast Guard wrote on Twitter.

What is the state of the search?

The search and rescue operation was in a critical stage on Thursday, with experts concerned that the five people on board may have run out of oxygen.

Rescue organizers rushed more ships and vessels to the site of the disappearance, hoping to locate the tiny vessel after detecting underwater sounds for a second straight day.

Those on board the Titan had a four-day supply of oxygen when they set off early on Sunday. But by Thursday, the estimated timeline of 96 hours had passed.

Ships and planes have searched 10,000 square miles (around 20,000 square kilometers) of surface water — roughly the size of Slovenia — in an effort to find the vessel some 400 nautical miles (740 kilometers) off the coast of Newfoundland, Canada.

The rescuers relocated two remotely operated vehicles capable of searching under the water and one surface vessel with sonar capability after a Canadian P-3 aircraft detected sounds possibly coming from Titan.

The 21-foot (6.5-meter) tourist submersible lost communication with its mothership less than two hours into its trip. It is unclear what the problem may have been.

The operating company, OceanGate Expeditions, charges $250,000 (€227,610) for a place on the submersible.

Who was on board the Titan?

Prominent Pakistani businessman Shahzada Dawood and his son, Suleman, were on board the vessel in the North Atlantic, their family said in a statement. Dawood is the vice chairman of one of the largest conglomerates in Pakistan, Engro Corporation, which has stakes in fertilizers, vehicle manufacturing, energy and digital technologies.

British billionaire Hamish Harding was also among the passengers, according to a social media post from a family member. Harding had earlier posted about his expedition on Instagram, saying that he was proud to join OceanGate’s Titanic mission.

OceanGate’s founder and CEO Stockton Rush was also later confirmed by the company to be on board.

Additionally, a French government source said that one of those on board was a French national — 77-year-old French explorer Paul-Henri Nargeolet.