"Each one in their own sector, don't throw pyrotechnics," the commentator repeated helplessly during the Sunday football match between Spartak Trnava and Slovan Bratislava.
Polish hooligans boasting on social networks about how they train in martial arts and then test their skills on the streets cared very little about what the organisers were telling them.
One, wearing the balaclava of the Polish football club Katowice, kicked a Slovan fan unconscious on the ground and then fled with a crowd of other extremists.
The people the Sme daily interviewed perceive the violence at the match as a sophisticated and planned attack by hooligans from Trnava, Katowice, and the Czech city of Ostrava.
First, they climbed the roof above the sector where the Slovan fans were located, throwing firecrackers at them. Afterward, dozens physically assaulted the Slovan fans, who had continuously been breaking rules and throwing firecrackers.
European countries have their own database of problematic fans about which the organisers of sports events should beware. They are supposed to share the information with other countries.
"Yesterday's match showed that the system failed to prevent the arrival of foreign visitors who represent a security risk," said analyst of the non-governmental think tank Globsec, Daniel Milo. He had previously worked as the Interior Ministry's expert on extremism.