At the 1956 Olympic Games, an extremely violent semi-final match in what sport was played between Hungary and Russia?

Question

What sport was part of the Olympic Games programme between 1896 and 1924, and returned as a full medal sport at the 1988 Olympics?

Answer 1

Water polo
Violence between the people and forces of the home countries of the two teams reverberated in the game. There were kicks and punches, and when one of the Hungarian players was left bleeding from a blow by a Russian player after play was halted briefly spectators invaded the concourse and forced permanent stoppage. The Hungarians who had been leading (4-0) were declared the winners.