The whole story is weird. Supposed out of a small crew there were 7 or 8 “First Captains” which is like a colonel in our military on board. Their names were published and they don’t look like techies. Based upon the time line the mother sub must have hyper drive because the injured were reported to be in a hospital near Murmansk a few hour after the incident. Murmansk is a few thousand miles from where this allegedly took place.
I'm going to guess the sub had a support ship, with helicopter, nearby. Sub surfaces, loads injured into helicopter, helicopter gets to medivac plane.