The passengers were all from the same cruise ship. The bigger aircraft apparently descended and collided with the smaller aircraft which was below it. The two missing passengers have been located, both deceased. I think at least one, if not more, of the deceased passengers had emigrated from South Africa but it wasn't reported in the media. (Edit: Media has confirmed the South African connection. https://www.thestar.com/vancouver/2019/05/15/bc-woman-and-her-family-members-killed-in-alaska-sea-plane-crash.html) I followed the details of this crash very closely as I'd flown with one of the airlines involved on the same sightseeing trip.