St. Petersburg police opened a criminal case Thursday after football fans clashed outside a McDonald's restaurant the night before.
Police reportedly detained six brawlers at the scene of the incident, which took place late Wednesday outside the fast-food giant's branch on Moskovsky Prospekt, while three others were hospitalized, Interfax reported.
In a video of what appears to be the aftermath of the brawl posted on YouTube, fans can be seen fleeing the scene of the violence. One fan lets off a flare as he chases after a group of supporters.
Leningrad region police told the news agency that the suspects would face hooliganism charges, which carry a maximum sentence of seven years in prison.
According to investigators, Wednesday night's brawl erupted after fans of St. Petersburg-based Zenit attacked local fans of Makhachkala-based Anzhi.
The motive for the violence appeared to be a Sunday confrontation between Zenit and Anzhi fans in Makhachkala, where two Zenit fans were reportedly beaten up after the two sides played out a 1-1 draw in the Russian Premier League.
Anzhi fans will be out in force on Thursday, when they are due to play a Europa League match against Dutch side AZ Alkmaar in Moscow's Lokomotiv Stadium.
Anzhi is not allowed to host home matches in European club competitions after international football officials expressed concerns over safety in Makhachkala, the capital of Russia's Dagestan republic.