This story is out of Yellow Stone National Park... a woman got too close to a bison and the bison decided to charge. The woman runs away... but trips and falls. She plays dead, and for about 20 seconds the bison surveys her... then runs away. Here's video:
You can see that a man grabbed a stick to use as a weapon in case he needed to defend the woman... do you think that would have worked?
Last month, a woman was gored by a bison in Yellowstone when she got too close. People have to be careful around wildlife!