At least 20 people have been injured in a fight that broke out in the stands during the anticipated Belgrade derby between local football clubs Partizan and Red Star Belgrade on Wednesday.

The brawl broke out in the first half of the game, with many foreign nationals among those involved in the fight and injured, suffering head injuries and burns from torches, and some stripped naked before police intervened.

While the interior ministry declined to mention their countries of origin, Serbian news site B92 has reported they are believed to be nationals from Greece, the Former Yugoslav Republic of Macedonia, and Croatia.

The ministry revealed on Thursday that Serbian police had since detained 26 people in connection with the fight.

Though fights at Belgrade derbies are not uncommon, according to reports this clash was between members of two rival Partizan supporters’ groups.

The game ended as a draw, with Red Star Belgrade ahead on the ladder.