We're not far from where the expedition launched on Sunday. It was an hour and 45 minutes into the dive that the vessel lost contact with its mother ship. It's been lost and silent since then. Now, *** massive rescue operation under way to find five people on board as oxygen levels could run out in *** matter of hours. Day, four of rescue operations to find the missing Titanic tourist Submersible is underway and with every passing hour, the situation becomes more dire. Right now, all of our efforts are focused on finding the but time is running out as available oxygen levels continue to drop. Experts estimate life support for the five passengers on board could run out by Thursday morning. Friends of those on board are holding out hope. I'm very optimistic. I keeping positive the Ocean Gate expedition sub left ST John's Newfoundland Sunday to explore the Titanic's wreckage. But less than two hours into the trip, it lost communication with its mother ship. The Titanic sits more than two miles below the North Atlantic Ocean Surface. The US Coast Guard say the deep water makes the search more difficult. You're dealing with *** surface search and *** subsurface search. And that makes it an incredibly complex operation. Rescue crews in both Canada and the US have surged an area about the size of Connecticut. The navy has been in touch with the Coast Guard and is working to provide personnel such as subject matter, experts and assets as quickly as possible. Crews are using sonar technology to try and locate the sub. On Tuesday night, they picked up banging noises. It could be *** glimmer of hope. The fact that they heard those noises last night is perhaps *** positive sign and certainly feeding some hope to those who are on the rescue mission and those who are hoping that the crew aboard the vessel will be found. We are looking to learn more about exactly what the sounds mean and whether or not rescue crews are any closer to locating the vessel. That is the first step before any rescue could possibly be considered reporting from Newfoundland Gloria Paso back to you.