On the Moskva, pretty big if true. Russia boasted it has so much air defence it couldn't be hit. Crew of around 510 as well.
Reportedly sending out multiple distress calls via Morse and cipher and some are reporting you can listen to the Morse messages.
US is sending a Blackhawk to the location so we'll get some sort of confirmation soon.
Not sure how Moscow would spin the fact their flagship and 500 crew got taken down if true.