A submersible with five people aboard has gone missing while on a tour of the wreckage of the Titanic off the coast of Newfoundland, Canada, according to officials.
The Coast Guard said the 21-foot submersible went underwater Sunday morning, and lost contact about 1 hour and 45 minutes later.
The Coast Guard was notified Sunday afternoon that the vessel belonging to the deep sea exploring company OceanGate was overdue, and crews immediately launched search and rescue operations, Rear Adm. John Mauger, U.S. Coast Guard 1st District commander, said at a news conference Monday.
The vessel was designed to have 96 hours of oxygen available, he said.
The search is taking place in remote waters about 13,000 feet deep, Mauger said.
"It is a challenge to conduct a search in that remote area, but we are deploying all available assets to make sure that we can locate the craft and rescue the people on board," Mauger said.
In an evening update, the Coast Guard said surface searches will continue “throughout the evening” by both the ship the sub launched from and by aircraft from the 106th Rescue Wing in Westhampton Beach, New York.
Two C-130 flights have already been completed and Canadian aircraft will continue their searches in the morning, the Coast Guard said.
MORE: New Titanic footage released from 1986 exploration of wreckOceanGate confirmed Monday that it lost contact with a submersible and five crew members were aboard.
“For some time, we have been unable to establish communications with one of our submersible exploration vehicles which is currently visiting the wreck site of the Titanic," the company told ABC News in a statement. "Our entire focus is on the wellbeing of the crew and every step possible is being taken to bring the five crew members back safely."
"We are deeply grateful for the urgent and extensive assistance we are receiving from multiple government agencies and deep-sea companies as we seek to reestablish contact with the submersible," the company said. "We pray for the safe return of the crew and passengers, and we will provide updates as they are available."
OceanGate's website says it offers paying customers the opportunity to explore the wreckage of the Titanic.
One of the passengers was Hamish Harding, who worked for the sales company Action Aviation, a colleague told ABC News.
"This is on the site of a wreckage, the wreckage of the Titanic, and so there's a lot of debris on the bottom, and locating an object on the bottom will be difficult," Mauger told Fox News on Monday.
"We have lives that are potentially at risk," he said.
On April 14, 1912, the Titanic hit an iceberg on its maiden voyage from England to New York. Over 2,200 passengers and crew were on board, and more than 1,500 people died when the ship sank.
The ship wreckage was found in 1985, almost 12,500 feet below the surface of the Atlantic Ocean.
ABC News' Miles Cohen, Josh Hoyos, Alex Faul, Nadine El-Bawab and Mark Guarino contributed to this report.