Fifty years ago, Peru's National Stadium in Lima became the site of what is today considered the worst tragedy to ever happen at a football stadium, during which 320 people were killed and 500 were wounded.
On May 24, 1964, Argentina's national team was winning 1-0 in a qualifying match for the Tokyo Olympic Games . Just two minutes before the end, the Peruvian team scored a goal to tie, but Uruguayan referee Angel Eduardo Pazos disallowed it. This decision enraged fans, and Víctor Vásquez, known as “Negro Bomba” (Black Bomb), jumped onto the filed. Many other fans followed him, with the intention of attacking the referee. In turn, police officers released dogs, who jumped on the fans.
Supporters of both teams who minutes before were peacefully watching the game began to fight with sticks and blades. In an attempt to control the situation, police threw tear gas. Hundreds tried to flee the stadium away from the gas, but the doors in the north gallery were closed, trapping people inside. Police had, in fact, closed them to try to persuade the spectators to calm down and go back to their seats.
Víctor Vásquez was arrested two days later. Another leading player in the tragedy, police commander Jorge de Azambuja, said later, “I ordered tear gas bombs to be thrown into the galleries. I can't say how many. I could have never imagined the terrible consequences.” There was no punishment for Commander Azambuja nor referee Pazos, who continued working in Uruguay.
The cause of death for many of the victims was internal bleeding or suffocation, almost all of them in the stairwells. Those who stayed inside the stadium were saved. On nearby streets, houses and businesses were destroyed.
The Curiosidades del fútbol (Curiosities about football) blog offered details  [es] about what happened that day:
El árbitro uruguayo Angel Eduardo Pazos había concedido el gol en primera instancia,pero ante las reclamaciones airadas de Perfumo lo había invalidado.La grada peruana estaba en plena ebullición ante el desenlace de aquella jugada.Es a partir de aquí cuando comienza toda la desgracia.
Uruguayan referee Angel Eduardo Pazos had said the goal was good at first, but following irate claims from [Argentinian Roberto] Perfumo, he disallowed it. The Peruvian gallery was up in arms after that decision. From here, the whole disgraceful thing began.
Meanwhile, the blog Jorge de Jesús Kbdto  [es] shared how Héctor Chumpitaz  recalled it. Chumpitaz was a Peruvian football player who was part of the national team that day at the National Stadium:
Regresando hacia nuestro lugar de concentración íbamos escuchando la radio y hablaban de 10, 20, 30 muertos. Cada vez que salían las noticias el número aumentaba: 50 muertos, 150, 200, 300, 350….
Después que llegamos a los vestuarios hubo personas que salieron y cuando regresaron nos contaron que había dos muertos. ¿Dos muertos?, preguntamos, pensando que uno ya hubiera sido demasiado.
As we returned to our pre-game meeting place, we were listening to the radio and they were mentioning 10, 20, 30 fatalities. Each time news were broadcast, the number kept going up: 50 dead, 150, 200, 300, 350….
After we arrived at the lockers, there were people who went out and told us there were two dead. Two dead? we asked, thinking that one would have been too many.
The blog Historia, tradición y fútbol  [es] listd other incidents that happened at the same stadium and analyzed the causes of the events on May 24, 1964:
Para entender la tragedia, no debe recurrirse exclusivamente a factores netamente futbolísticos o deportivos –como el error humano de tener cerradas las puertas de acceso al estadio, el fanatismo del embriagado Víctor Matías Campos Vásquez, alias “negro Bomba”, o las desacertadas medidas policiales de arrojar gases lacrimógenos a las tribunas Oriente y Norte. Hubo otros factores que explican la descomunal cantidad de muertos y se encuentran más allá de lo meramente futbolístico.
To understand the tragedy, we should not focus exclusively on purely football or sports factors – take the human error of having closed the entrance doors, the fanaticism of inebriated Víctor Matías Campos Vásquez, aka “negro Bomba”, or the unwise measures of the police, such as throwing tear gas at the east and north galleries. There were other factors that explain the huge number of fatalities that go beyond purely football issues.
On Twitter, there were many users who remembered the date, and shared images and reflections:
— Revista Somos (@SomosElComercio) Mayo 24, 2014 
This is how the press reported on the tragedy at the National Stadium.
Habla sobreviviente de la tragedia en el Estadio Nacional (VIDEO) http://t.co/OUniyWpRIR 
— Diario Correo (@diariocorreo) Mayo 24, 2014 
Testimony by a survivor of the tragedy at the National Stadium (VIDEO)
— Perú News (@PeruNews) Mayo 24, 2014 
This is how the press reported the tragedy at the National Stadium: On May 24, 1964, the regrettable…
Hoy se cumplen 50 años de tragedia del Estadio Nacional. Y parece que no aprendemos de nuestros errores. Dile NO a la violencia en el fútbol
— vicente cisneros (@vicentgol) Mayo 24, 2014 
Today we mark 50 years since the tragedy at the National Stadium. And it seems we don't learn from our mistakes. Say NO to violence in football.
Verguenza #Peru  gobierno alquilo estadio nacional hoy pa concierto d salsa mismo dia de 50 aniversario d mayor tragedia futbol:320 muertos
— luis jaime cisneros (@ljcisneros) Mayo 25, 2014 
Shame! Peru government rented the National Stadium today for a salsa concert, on the same day of the 50 anniversary of our biggest football tragedy: 320 killed.