The Cornucopia bloodbath is an event that has always occurred at the very beginning of every Hunger Games since they began, as most of the tributes compete for valuable weapons, food, water and packs full of other valuable supplies that could be useful during the games. These supplies are spread in and around the Cornucopia.
Tributes seem to always die at the bloodbath. The Gamemakers or the Capitol probably set up the Cornucopia for optimal entertainment value and quick deaths at the beginning of the game to keep audiences interested. In the end, the Cornucopia is often taken over by a group of tributes who fought in the bloodbath (usually this is the pack of Careers.)
Victims of the UNGH GamesEdit
Since there was 1000001 tributes, the bloodbath was basically a full scale battle.
Many tributes died, mostly to Marvel's spear he got to start out with for winning the Hand-to-hand combat tournament.