BREAKING: OceanGate crew and passengers are declared lost.

ABC NEWS: All passengers are believed to be lost after a desperate dayslong search for a submersible carrying five people vanished while on a tour of the Titanic wreckage off the coast of Newfoundland, Canada.

The 21-foot deep-sea vessel, operated by OceanGate Expeditions, lost contact about an hour and 45 minutes after submerging on Sunday morning with a 96-hour oxygen supply. That amount of breathable air was forecast to run out on Thursday morning, according to the United States Coast Guard, which is coordinating the multinational search and rescue efforts.

OceanGate feared lost after debris recovered.

CNN: OceanGate said Thursday that it believes the passengers of the Titanic-bound submersible have “sadly been lost,” according to a statement from the company.

“We now believe that our CEO Stockton Rush, Shahzada Dawood and his son Suleman Dawood, Hamish Harding, and Paul-Henri Nargeolet, have sadly been lost,” the company said in a statement.

“These men were true explorers who shared a distinct spirit of adventure, and a deep passion for exploring and protecting the world’s oceans,” according to the statement. “Our hearts are with these five souls and every member of their families during this tragic time. We grieve the loss of life and joy they brought to everyone they knew.”

Debris found on ocean floor has been assessed to be from the external body of the Titan sub

The debris discovered within the search area of the missing Titanic submersible has been assessed to be from the external body of the sub, according to a memo reviewed by CNN.

The search for the crew capsule of the Titan vessel continues, the memo says.

The debris was located on the ocean floor, roughly 500 meters (about a third of a mile) off of the bow of the Titanic, and it was found around 8:55 a.m. ET.

It was discovered by a remotely operated vehicle that was searching the seafloor, according to the US Coast Guard.

The discovery came at an urgent time for the search and rescue effort. Experts say the sub and its five passengers would be reaching the limit of the sub's roughly 96 hours of life support, having gone missing Sunday morning.