Condolences to the family of the deceased. Healing prayers for all the injured riders and for a speedy recovery.
It's easy to guess some of the reasons something like this would happen, but hopefully they'll have a followup and report what caused the car to enter their lane without warning.
Yesterday a girl in a car almost hit me. She was talking on a cell phone and turning in a double turn lane next to me. When I twisted the throttle and sped up, (visualize loud pipes at throttle) she jerked back into her lane. She was simply not paying attention to her driving. I would have liked to give her my opinion of her actions at that moment. Could have been not so pretty - for me.
The event in Michigan could be any of us on our group rides. That's why I'm a little more Conservative on blind corners than some. I simply will not assume the way is clear until I know for a fact and can see what's around the corner -- especially on roads I do not ride regularly.
God bless to all and safe riding.