Very tragic. Be aware of your surroundings, how to save yourself, then help others if you can.
I have seen these boats in person, I have read all the tragic stories of the accidents.
It was probably taking on water, then flipped.
I am pretty sure the one in Hot Springs (that we almost got on) just has a rear end seal replaced and it blew out. Took on water quickly, the people saw it coming up into the floor and made no effort to get off it.
Get your life jacket and get off! Do not rely on someone to tell you what to do.
My husband and I would have looked at each other and said "GET OFF" now, and that is that.