Video of the world's most famous polar bear's sudden death has surfaced.
The footage shows Knut walking in circles and then collapsing into a pool prior to sudden death at a Berlin zoo.
Zookeeper Heiner Kloes told the press that the zoo staff was shocked. One moment, Knut was in the water, and the next, he was dead. He said Knut wasn't sick, and they don't know why he died.