Nope. Not good.
This ridiculous footage is from yesterday's derby between Red Star Belgrade and Partizan Belgrade. Called the "Eternal Derby," the rivalry is the most contentious in Serbia, and one of the most intense rivalries in the world. Yesterday, with home side Red Star up 1-0 early in the second half, Partizan fans first began throwing flares on the pitch, before lighting several fires on the terraces in their own cheering section.
More fans joined in, because they are insane, and as you can see in the video, started throwing debris into the separate infernos. Before long, hundreds of away fans were dancing around several raging fires. The referee had to stop play until smoke cleared the stadium, and fire trucks were brought in to quell the flames.
Red Star still won.
h/t to Todd