In British Columbia, a grizzly bear inflicted minor wounds on a couple of hunters. The men were sleeping in their tent when the bear attacked. After their skirmish, the men backtracked and discovered the bear had been stalking them for some time.
Most grizzly attacks don't start out predatory. They're more likely to happen when people surprise the bear or approach its cubs. That's why playing dead sometimes works: the bear isn't looking for a meal, it just wants to intimidate. Unfortunately, once the action starts, a grizzly sometimes decides to make a meal even if it didn't start out looking for one. That's why playing dead doesn't always work.