Tiger kills 6-year-old at zoo

I read in the papers yesterday about a tiger which killed a little girl in a zoo in China. The incident occured while the girl and her relatives were standing behind the tiger waiting for a photo-shoot. When the cameras flashed in front of the tiger, it turned around suddenly and bit the girl in the head. Animal trainers hit the tiger repeatedly with sticks and wooden stools until it released the girl a minute later. The girl died in hospital later. The tiger was one of the six which performed at a circus in the zoo.

It is very unfortunate that the girl died. There had been many other cases similar to this. I wonder what made the tiger go berserk when the cameras flashed. Considering it being a circus tiger, and I have read about the cruelty to animals behind-the-scences in circuses, I thought perhaps it was reminded of the torture it endured (if any) when the cameras flashed. Zoos are places where people can observe the animals, but how natural can the behavior of the animals be when they are kept in the same enclosure for most or all their lives. Who wouldn't go mad if they sit in prison all day? Visitors to the zoo, however, are not shown this side of the story.