A “debris field” has been found in the search area for the missing OceanGate Expeditions sub that explores the Titanic wreck site with five people aboard, according to the Coast Guard out of Boston.

The 21-foot submersible has been missing in a remote area of the North Atlantic Ocean, about 900 miles off of Cape Cod, since Sunday. The 96-hour oxygen supply on board was expected to expire on Thursday.

Early Thursday morning, a Canadian vessel Horizon Arctic deployed a remotely operated underwater vehicle (ROV) — reaching the sea floor to search for the missing sub.

“A debris field was discovered within the search area by an ROV near the Titanic,” the First Coast Guard District tweeted a few hours later on Thursday.

“Experts within the unified command are evaluating the information,” the Coast Guard added.

In Boston Thursday afternoon, the Coast Guard is scheduled to host a press briefing to discuss findings from the Horizon Arctic’s ROV on the sea floor near the Titanic.

On Wednesday, officials had reported that “banging” underwater noises were heard in the search area. As a result, the Coast Guard redirected ROV operations to explore the sounds.

The Navy has sent a Flyaway Deep Ocean Salvage System to the search area. That’s a lift system designed to recover large, bulky, and heavy undersea objects, such as aircraft or small vessels.

The search started Sunday afternoon when the Coast Guard received a report of an overdue 21-foot submersible from the Canadian Research Vessel Polar Prince with five people on board, diving to view the wreckage of the Titanic.

The sub is located about 900 nautical miles east of Cape Cod, and the maximum depth of the dive goes down almost 2.5 miles to the ocean floor.

The submersible was launched at 8 a.m. on Sunday, and was expected to resurface at 3 p.m. But one hour and 45 minutes into their dive, they lost contact with the Polar Prince.