(NEXSTAR) – Fat Bear Week is off to a violent start this year. The scheduled reveal of the bracket and all the chunky contestants was pushed back by a day after one bear, No. 469, attacked and killed another bear, No. 402, Monday morning. The attack was seen live on webcams at Katmai National Park, the Park Service said. The Alaska national park puts on Fat Bear Week annually as a way to raise awareness about the 2,200-pound brown bears that live in the park. Every year, they gorge themselves on salmon, rapidly putting on pounds to prepare for the long, cold winter. A brown bear snags a sockeye salmon in mid-air on August 11, 2023 at Brooks Falls, Alaska within the Katmai National Park and Preserve. The bears feast in large numbers at the falls between July and September, as millions of salmon swim upstream to spawn. Many of the same bears return to the falls annually, gorging on salmon to fatten up before hibernating for winter. The bears have become something of an internet sensation, as "bearcams" livestream bear activity at and around the falls to viewers worldwide. (Photo by John Moore/Getty Images) The contest, in which people vote on their favorite and most impressively fat bear, is lighthearted in spirit. It often spawns memes and celebrates the bears' impressive ability to transform so rapidly. But this year's deadly kickoff had a sobering reminder these are wild animals. "National parks like Katmai protect not only the wonders of nature, but also the harsh realities," park spokesperson Matt Johnson said in a statement. "Each bear seen on the webcams is competing with others to survive." McDonald’s is bringing back its famous ‘Boo Buckets’ for the Halloween season Katmai National Park ranger Sarah Bruce said it wasn’t known why the bears started fighting. The same cameras, which are set up in the park to livestream footage of the bears all summer, also captured a male bear killing a cub that slipped over the waterfall in late July. “We love to celebrate the success of bears with full stomachs and ample body fat, but the ferocity of bears is real,” said Mike Fitz, explore.org’s resident naturalist. “The risks that they face are real. Their lives can be hard, and their deaths can be painful.” The killer bear 469 is a male and the victim was female. Bear 402 was originally a contestant in this year's competition. After the delay, the brackets were revealed Tuesday afternoon. Voting opened Wednesday on explore.org. More than 1.3 million votes were cast last year. One first-round match pits Bear 903, an 8-year-old male who was given the nickname Gully after he developed a taste for seagulls, against Bear 909, the mother of Bear 909 Jr. The winner faces a two-time champion, a bear so large he was given the number of the equally massive airplane, Bear 747. In the other half of the bracket, the first-round match has Bear 856, an older male and one of the most recognizable bears on the river because of his large body, challenging a newcomer, Bear 504, a mother bear raising her second known litter. The winner will face perhaps the largest bear on the river, 32 Chunk, a 20-year-old male who once devoured 42 salmon in 10 hours. He's estimated to weigh more than 1,200 pounds. The Associated Press contributed to this report.