A sub that went missing while carrying five people to the wreckage of the Titanic has about 40 hours of breathable air left, the U.S. Coast Guard said Tuesday afternoon.
The sub had about 96 hours of oxygen at most onboard, officials said.
A Canadian research vessel lost contact with the sub during a dive Sunday morning about 900 miles east of Cape Cod, Massachusetts, and U.S. and Canadian authorities have been searching for it.
Coast Guard Capt. Jamie Frederick told reporters during a news conference that the "about 40 hours of breathable air left" was an estimate based off of the 96 hours of available oxygen.
He said authorities were working around the clock on the search in the Atlantic for the missing sub, calling the effort "an incredibly complex operation."
"We will do everything in our power to affect a rescue," Frederick said. "... There is a a full-court press effort to get equipment on scene as quickly as we can."
Pakistani businessman Shahzada Dawood, his son Suleman, British explorer Hamish Harding and French explorer Paul-Henri Nargeolet were on the sub, CBS News has confirmed.
BBC News confirmed Stockton Rush, the CEO of OceanGate Expeditions, the U.S.-based company that planned the voyage, was also on the vessel.
The Coast Guard said the last recorded communication from the sub was about an hour and 45 minutes into Sunday's dive.
Since the sub went missing, the Coast Guard, Canadian coast guard, U.S. Navy and Air National Guard have searched a combined area of about 7,600 square miles, an area larger than the state of Connecticut, Frederick said.
Search efforts continued Monday night and into Tuesday, he said.
A pipe-laying vessel arrived in the search area Tuesday and sent a remotely operated vehicle into the water to look for the sub at its last-known position.
With search flights scheduled to fly over the area throughout the day, a Canadian coast guard vessel was expected to arrive Tuesday evening, Frederick said.
Several other Canadian vessels and a U.S. Coast Guard cutter were en route to the area.
The U.S. Navy was working on deploying military assets to aid the search, Frederick said.
