It’s becoming a race against time for the search-and-rescue vessels being deployed in droves to try and find the Titan, the missing Titanic-exploring sub before it’s too late. The now infamous OceanGate Expeditions submersible, with five passengers on board, is expected to run out of oxygen at some point on Thursday, so every second is critical. Under these auspices, the U.S. Coast Guard provided an update on Twitter on Thursday that an underwater vessel has located a debris field near the Titanic, but provided no indication as to whether the debris is from the Titan.

The U.S. Coast Guard’s message explained, “A debris field was discovered within the search area by an ROV near the Titanic. Experts within the unified command are evaluating the information.” It also noted that there will be another press briefing to update the situation at 3 p.m. Eastern time.

At this point, the search has passed the critical 96-hour mark when breathable air was assumed to run out, but the mission remains a search-and-rescue operation at present. It’s possible that if the passengers took measures to conserve breathable air, the air supply could be extended slightly.

Guillermo Sohnlein, a co-founder of OceanGate who left the company in 2013, said in a statement that Thursday “will be a critical day in this search and rescue mission, as the sub’s life support supplies are starting to run low.”

Among the many emergency vehicles being deployed to search for the missing sub include: a French-operated deep-diving robot equipped with with cameras, lights and arms; an underseas Canadian robot that had already reached the sea floor; and a U.S. Navy machine that can help recover heavy objects from oceans.

The ordeal of the missing sub has had many strange twists and turns, and has received round-the-clock media attention. Today will be no exception as the next 24 hours will likely determine the fate of the passengers on board.