There was still ten minutes to go until kick-off in Zagreb, Yugoslavia, when the fans of Dinamo Zagreb crashed through the metal fences that separated the stands from the pitch.
The Croatian ultras, the Bad Blue Boys, had been trading insults with their most bitter rivals, Red Star Belgrade, and sporadic violence had broken out throughout the stadium.
What happened next was described by sports journalist Boris Mutić as a “circle of hell”, as riots that began in the ground spilt onto the streets. In perhaps the most infamous incident, Zvonimir Boban, Dinamo’s captain, waded into the crowd to stop a police officer attacking a fan.
Within a year, the ultras of the Croat Bad Blue Boys and the Serb Delije were fighting each other on the battlefield, after Croatia declared independence and ended up in a war with Yugoslavia.
With the Red Star Belgrade fans that day was Željko "Arkan" Ražnatović, the head of the Delije hooligans and later supreme commander of the Serb Volunteer Guard.
30 years on, and May 13, 1990, is still ranked among the most infamous football games in history: perhaps the only European football game in history credited with "starting a war".
Certainly by the Bad Blue Boys, whose ranks were among the first to join the paramilitary groups that fought in the Balkan conflicts, which killed more than 20,000 people between 1992 and 1995.
On a monument commemorating the riot outside Maksimir Stadium in Zagreb, a plaque pays tribute to "Dinamo fans for whom the war started on May 13, 1990, and ended with them laying down their lives on the altar of the Croatian homeland.”
The reality, of course, is more complicated.
“There is no doubt that sports in late-socialist Yugoslavia can be described as a ‘national motor’ and that the Maksimir riots reflected the political tensions which existed and were developing in the socialist federation at that time,” Dario Brentin, an associate researcher at the Centre of Southeast European Studies of the University of Graz, told Euronews.
“[But] the ‘war’ definitely did not start at Maksimir on May 13 1990.”
In fact, there were a number of other football-related controversies that happened over the course of that summer in the former Yugoslavia and which aided the slide into conflict.
On June 3 during a World Cup qualifier against the Netherlands, a mostly Croat crowd “shouted down the Yugoslav national anthem, insulted Yugoslav players, cheered for the opposition and jeered national coach Ivica Osim.
In September 1990, Hajduk Split fans burned the Yugoslav flag during a league game and raised the black-and-white checked Croatian flag, while chanting for independence.
For Brentin, the fascination around what happened on 13 May 1990 is understandable - there are not many occasions in European history when a football game is said to have started a war - but a result has been a lack of perspective on cause and consequence of the event.
"The mythologised narrative has been furthermore widely popularised amongst football fans (and beyond) through documentaries, journalistic pieces and football fanzines,” he said.
Over the years, the question of attendance at Maksimir has become important in certain circles for both Croats and Serbs. Aleksandar Vučić, the current president of Serbia, has claimed to have been there on May 13, 1990, in an attempt to bolster his man-of-the-people image.
"It's a bit like the Sex Pistols gig in 1976 at the Manchester Free Trade Hall," said James Montague, a football writer and author of 1312: Among the Ultras.
"A lot of people claim they were there, and that's because for a lot of ultranationalists it was a very significant moment. It marked the descent into ultranationalistic conflict."