I'll bet they weren't wearing seat belts. A rollover should not be fatal if they were strapped in.
That is probably the case, and I can't help but wonder if these people didn't use the seatbelts in part because they already felt "so safe" in their SUV's. My point about SUV's is this, they aren't as "safe" as generally accepted by the public. They tend to have dangers inherent in their design (poor handling and stopping, rollovers) that cars don't tend to have. I have seen many SUV drivers attempt maneuvers that I would only consider doing in a sports car. Some pretty dumb behaviour.