The Estadio Nacional disaster occurred on 24 May 1964 at the Estadio Nacional in Lima, Peru, during a match between football teams from Peru and Argentina. An unpopular decision by the referee outraged the Peruvian fans, who invaded the pitch. Police retaliated by shooting tear gas into the crowd, causing a mass exodus. The deaths mainly occurred from people suffering from internal haemorrhaging or asphyxiation from the crushing against the steel shutters that led down to the street. The incident is considered one of the deadliest incidents in the history of association football.