Five people, including the company CEO, were aboard the sub when it imploded.
All passengers are believed to be lost after a desperate dayslong search for a submersible carrying five people that 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 was coordinating the multinational search and rescue efforts.
Three U.S. Air Force C-17 cargo aircraft will be transporting commercial equipment from Buffalo, New York, to Newfoundland, Canada, to help with the search efforts, according to a U.S. official.
-ABC News' Luis Martinez
Efforts to locate the missing submersible are ongoing, and the "complex" search covers an area larger than the state of Connecticut, Coast Guard Capt. Jamie Frederick said at a news conference Tuesday.
Crews are scouring the ocean 900 miles east of Cape Cod and 400 miles south of St. John's, Canada, he said.
The missing five-person crew on the submersible has about 41 hours of oxygen left, Frederick noted.
"We will do everything in our power to effect a rescue," Frederick said.
"We have a group of our nation's best experts," he said, and once the sub is located, "those experts will be looking at what the next course of action is" to rescue the crew members.
"Our thoughts and prayers are with the crew and their families and their loved ones," Frederick added.
In 2000, Dr. Michael Guillen, then an ABC News correspondent, was filming from the wreck of the Titanic when his vessel became trapped in the propeller.
"When we collided with the propeller, and I started seeing those big chunks of metal raining down on us … the first reaction I had was, 'This can't be happening,'" he recalled to ABC News on Tuesday.
"We got caught by this underwater turn and just drove us right into the blades," Guillen said.
"This voice came into my head and said, you know, 'This is how it's going to end for you,'" he recalled. "I'll never forget those words."
"I'm very aware of what these poor souls on board the ship the Titan are experiencing," he said. "I am just heartbroken about it."
At the request of French President Emmanuel Macron, a French ship named Atalante is diverting to the area of the missing submissive and should reach the area Wednesday night.
The ship has an exploration robot that can dive up to 4,000 meters, according to a spokesman for France's Ifremer Institute.
