BOSTON — Sonar picked up banging sounds on Tuesday from underneath the water in the North Atlantic Ocean while searching for a submersible with five people onboard that went missing two days earlier on a dive to the Titanic wreckage, according to an internal US government memo on the search.

It was unclear when the banging was heard Tuesday or for how long, based on the memo obtained by CNN. A later update sent Tuesday night suggested more sounds were heard though it was not described as “banging.”

“Additional acoustic feedback was heard and will assist in vectoring surface assets and also indicating continued hope of survivors,” the update reads.

A Canadian P3 aircraft also located a white rectangular object in the water, according to that update, but another ship set to investigate was diverted to help research the acoustic feedback instead, according to that update.

Rolling Stone was first to report the news Tuesday night.

OceanGate told CNN they have no information to share on this when reached for comment. CNN has also reached out to the US Coast Guard in Boston and Canadian authorities for comment.

The report comes amid a multinational race against time to find the submersible and its five passengers before their oxygen runs out.

As the massive search stretched into its third day, more ships and aircraft have joined the mission.

A spokesperson for the US Navy said the military branch is sending subject matter experts and a “Flyaway Deep Ocean Salvage System” to help in the rescue mission for the commercial submersible, which disappeared Sunday morning and as of Tuesday night, had just over 30 hours of oxygen left.

The system has the capacity to lift and recover large, bulky and heavy undersea objects, like the small submersible.

The equipment and personnel were expected to arrive at St. John’s, Newfoundland, by Tuesday night, the spokesperson said.

The US Coast Guard and the Royal Canadian Air Force are also deploying more aircraft and vessels to aid in the search for the 21-foot submersible. The fleet of assets joining the operation include a Canadian pipe-laying vessel with underwater capabilities, along with other vessels and aircraft. — CNN