There is a lot we don’t know. We do know bear attacks basically fall into 2 broad categories
Defensive Attacks –Â Maybe there is food involved, a surprise or cubs. These are details. The basic problem is a person ends up too close, the bear feels threatened and it attacks instead of running away. Being smart goes a long way to preventing this kind of attack. The basic rule is “stay away from the bear and don’t surprise them.” Bears are less likely to leave an area if there is food so they might let you get closer before reacting one way or the other.
Predatory-Â The bear is hungry and you look tasty. These may involve a bear that circles or stalks a person or rushes in as a sort of test of how they react. These are more rare but you might need more bear spray to deter them. A friend dealt with a predatory bear in Alaska and apparently several people with bear spray were required. Eventually authorities shot the bear because it was still in the area.
Dogs can be chased and bring a bear to you. So I’d be careful hiking with a dog.
Now in this case it’s possible the dog provoked the attack and the bear took out both people (possibly encountering first one, than the other so the “safety in numbers” didn’t work). On balance I’d guess it was a predatory bear though. That would explain it hanging around to be shot by the rescue party.
So what’s the lesson to learn? Well sometimes you are in the wrong place at the wrong time. There was a guy who randomly got hit by lightning in Big Bend National Park. Bad things happen. It’s possible the dog was a non issue and these folks just met the wrong bear. Or it’s possible the dog brought the bear in.
The only lesson I can think of is be careful with dogs. And maybe consider going a bit heavier on the bear spray than some do. If a bear is really persistent and comes back after a good spraying that might be a predatory bear. I’d want more spray and I’d be leaving the area asap.