The latest information is the girl fell through a porthole while her family was playing shuffleboard. I'm surprised there isn't more information, pictures, or footage of exactly what happened (I guess Disney is controlling that), but some folks are saying all the portholes have plexiglass, others are saying some portholes don't, but I'd have to imagine this is a negligence nightmare for Disney if a child could somehow fall through one.
I'm also surprised (but also not) that we haven't seen the dad/child doing tv interviews yet.