Who were the 5 people killed on board the OceanGate Titanic submersible

After days of desperate searches throughout the Atlantic Ocean, the U.S. Coast Guard announced Thursday that the five passengers aboard the missing submersible vessel were killed when vessel suffered a catastrophic implosion.

Stockton Rush, Shahzada Dawood, his son Suleman Dawood, Hamish Harding and Paul-Henri Nargeolet were inside the vessel that embarked on the deep-dive tour, according to OceanGate, the company that operated the submersible. Their families were notified after debris of the vessel was found on the ocean floor, according to the Coast Guard.

"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," OceanGate said in a statement Thursday.

The submersible was designed with life support to sustain five crew members for 96 hours. On Thursday, the Coast Guard said it found debris on the ocean floor that was consistent with "catastrophic loss of the pressure chamber," roughly 1,600 feet from the Titanic wreckage.

The investigation into the incident is ongoing.

Here's what we know about the victims.

Hamish Harding

Hamish Harding was no stranger to exploration.

Harding circumnavigated the Earth in 2019. He made a dive in 2021 to the deepest point on earth, Challenger Deep, in the Mariana Trench. And he traveled into space last year aboard Blue Origin's New Shepard.

Harding, a British businessman and chairman of Action Aviation, previewed his dive to see the Titanic shipwreck in a Facebook post.

"Due to the worst winter in Newfoundland in 40 years, this mission is likely to be the first and only manned mission to the Titanic in 2023," he posted on Sunday. "A weather window has just opened up and we are going to attempt a dive tomorrow."

Harding, a licensed air transport pilot who holds three Guinness World Records, was "an extraordinarily accomplished individual who has successfully undertaken challenging expeditions," Action Aviation said in a statement.

Along with his ocean dives and blasting off to space, he helped with "the reintroduction of Cheetahs from Namibia to India" and "has been to the South Pole a number of times," the company said. Harding was inducted in 2022 as a Living Legend of Aviation.

On Thursday afternoon, Harding's family and Action Aviation released a statement saying they were "united in grief with the other families who have also lost their loved ones on the Titan submersible."

"Hamish Harding was a loving husband to his wife and a dedicated father to his two sons, whom he loved deeply," the statement read. "He was a passionate explorer – whatever the terrain – who lived his life for his family, his business and for the next adventure. What he achieved in his lifetime was truly remarkable and if we can take any small consolation from this tragedy, it’s that we lost him doing what he loved."

"We know that Hamish would have been immensely proud to see how nations, experts, industry colleagues and friends came together for the search and we extend our heartfelt thanks for all their efforts," the family and company added in their statement.

Shahzada and Suleman Dawood

Shahzada Dawood was vice chairman of Engro Corporation Limited, a sprawling business headquartered in Karachi, Pakistan. Suleman Dawood is his son, the family said in a statement.

The Dawoods were both British citizens, according to a colleague.

Shahzada Dawood, a husband and father of two, loved photography, gardening and exploring natural habitats, according to the family.

Suleman Dawood, a university student, was passionate about science fiction literature and learning new things.

Samad Dawood, Shahzada's brother, told ABC News he, his sister and his father all traveled to Newfoundland with hopes of better news.

Samad Dawood broke down in tears as he reflected on his nephew.

"He was so filled with humbleness and gratitude," he told ABC News. "I think it's sad but also amazing that... his death also brought the world together, and I thank him for it."

Samad Dawood said his brother "inspired in us audacity from a very young age."

"He was always the kind of person who had love for the world," Samad Dawood said. "He was a guy who just wanted to go out there, experience what the world had to offer, even though he himself pushed himself to do it."

The Dawood family released a statement Thursday expressing gratitude for everyone involved in the rescue operations.

"Their untiring efforts were a source of strength for us during this time," they said in the statement. "We are also indebted to our friends, family, colleagues and well-wishers from all over the world who have stood by us during our hour of need. The immense love and support we receive continue to help us endure this unimaginable loss."

"We extend our heartfelt condolences to the families of the other passengers on the Titan submersible," the family added. "At this time, we are unable to receive calls and request that support, condolences and prayers be messaged instead. Details of their final rites in this world will be announced soon."

In a statement Thursday night, Engro offered its condolences for both Shahzada and Suleman Dawood.

"With heavy hearts and great sadness, we grieve the loss of our Vice Chairman, Shahzada Dawood, and his beloved son, Suleman Dawood," the company said in the message. "Our thoughts and prayers are with the Dawood family at this tragic time."

"We extend our heartfelt condolences to the family, colleagues, friends and all those around the world who grieve this unthinkable loss," it added.

Paul-Henri Nargeolet

Paul-Henri Nargeolet, known as PH, a diver and Titanic researcher, was among the passengers. He was the director of Underwater Research at RMS Titanic Inc., according to the company.

Nargeolet led six expeditions to the Titanic site, most recently in 2010.

Stockton Rush

According to OceanGate's website, Stockton Rush "oversees OceanGate’s financial and engineering strategies and provides a clear vision for development of 4,000 meter (13,123 feet) and 6,000 meter (19,685 feet) capable crewed submersibles and their partner launch and recovery platforms."

Rush, who studied aerospace engineering at Princeton University and obtained an MBA from the University of California, Berkeley, "has written numerous engineering articles on crewed submersible vehicles in subsea operations," OceanGate's website said.

ABC News' Matt Foster, Miles Cohen, Mark Guarino, Emily Shapiro, Peter Charalambous, Sam Sweeney, Laryssa Demkiw, Gio Benitez and Victoria Beaule contributed to this report.