Video has emerged purporting to show the death of Knut the polar bear at the Berlin Zoo.
The video shows Knut, a media sensation, in the enclosure Saturday afternoon and looking agitated before suddenly collapsing and falling into his pool.
Berlin Zoo said Tuesday in a statement that a preliminary necropsy conducted Monday on Knut revealed "significant changes to the brain, which could be seen as the reason for the sudden death."
Zookeepers say they don't know what killed the 4-year-old bear, hand-raised at the Zoologischer Garten Berlin after being rejected by his mother at birth.
This is awful," said Berlin's mayor Klaus Wowereit said, according to The Sydney Morning Herald. "We had all taken him to our hearts. He was the star of the Berlin Zoo."
The celebrity news site TMZ.com carried news of his death and says People for the Ethical Treatment of Animals' German branch had previously complained that his mother and other bears were tormenting Knut. And a PETA rep told TMZ that polar bears don't belong in captivity.
The DPA newswire reported zoo official Heiner Kloes as saying an autopsy would be carried out on the bear.