Banging sounds heard during Titan search, according to internal US government memo

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. Crews detected banging sounds every 30 minutes – and four hours later, after additional sonar devices were deployed, banging was still heard, according to the memo. It was unclear when on Tuesday the sound was heard or for how long, based on the memo obtained by CNN.