Well the flash or something make have seemed unpeaceful to the Bison. Wild animals are just that God's beauty put there to admire but be careful. RTR!
People were crowding the bison. Witnesses said the crowd was 5-10
feet from it for 20 minutes. Then finally it charged.
Rangers at YNP set a minimum range of 25
YARDS distance for people who approach bison. That was the problem.
Plus, everyone else was faster running away than the little girl!