Fat Bear Week is a celebration of the brown bears of Katmai National Park and Preserve in Alaska. It’s typically a time of joy and friendly rivalry among humans cheering on their favorite ursine competitors. Fat Bear Week didn’t start as planned this year. The park and its livestream partner Explore.org delayed the announcement of contestants after a shocking bear-on-bear battle in the Brooks River left one bear dead.

The fight occurred on Sept. 30, the scheduled day for the Fat Bear Week bracket reveal. The competition is designed a bit like March Madness in NCAA basketball. There’s a lot of hype around the reveal of the contestants, which are the pudgiest bears in the park. Fans pore over the bears’ biographies and choose which ones they’ll vote for during the single-elimination tournament. The voting continues until a final fat bear emerges triumphant.

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Explore.org naturalist Mike Fitz addressed the fight during what was supposed to have been a bracket reveal event for the Fat Bear Week contestants. “The situation that we dealt with today was difficult to witness,” Fitz said. “We love to celebrate the success of bears with full stomachs and ample body fat, but the ferocity of bears is real. The risks that they face are real. Their lives are hard and their deaths can be painful.”

Bear fans watched the battle unfold on a livestream. Two bears met out in the river and engaged. An older female known as 402 fought with an older male known as 469. The male bear killed 402. “I don’t know why a bear would want to expend so much energy trying to kill another bear,” said Katmai ranger Sarah Bruce, saying it’s uncommon to see a bear predating another bear.

Caution, the following video includes footage and analysis of the bear attack:

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The Fat Bear Week bracket reveal took place on Tuesday evening instead. The 12 contestants include some familiar faces. Last year’s winner, 128 Grazer, is back to defend her crown. Heavyweight 32 Chunk, a dominant bear on the river, has been a top competitor in recent years, but has never won Fat Bear Week. “He excelled this summer in a place where conflict among bears is necessary to maintain rank and access to the most productive fishing spots,” Explore.org said in Chunk’s bio. The 2022 champion 747, known as “Bear Force One,” is also in the mix.

There’s an added edge of intrigue this year since Chunk killed one of Grazer’s cubs earlier in the year. “Her story this year demonstrates that even the most skilled and formidable mother bears experience hardship and loss,” Explore.org said. While Fat Bear Week is fun, the bear fight and the death of Grazer’s cub highlight the harsh reality of life in the wild. There’s room for both delight and sorrow when engaging with Fat Bear Week.

Fat Bear Week voting kicks off on Oct. 2 and the final round takes place on Oct. 8. Grazer rolls in as a favorite, and her backstory might sway bear fans into her camp. But nothing is certain. There could be upsets. It’s all down to the human voters now.