The world is mourning the sudden death of Berlin’s most famous polar bear. A tourist caught the exact moment when 4-year-old Knut keeled over and died in his enclosure at the Berlin Zoo.

Knut was born in captivity at the Berlin Zoo in 2006. He became an overnight celebrity when a German tabloid published a quote from an animal rights activist protesting keeping the bear in captivity. Knut’s worldwide fame spawned toys, media specials, DVDs, and books.

In the video, it appears as if Knut is sick. Poisoned maybe? The video starts off with a disoriented Knut chasing his tail around in circles. Eventually, he is unsteady on his feet and loses his balance. Finally, Knut lets out a loud groan and keels over backwards into the water.

Tourists can be heard screaming in the background as Knut thrashes in the water for a few seconds before drowning. How sad.