They were all later released. Police had to take many of the hooligans into custody in the Olympic Stadium during the game itself, but some fights broke out downtown before Russia's 3-0 victory over Finland.
The main clash occurred on the city's main boulevard Mannerheimintie, when a parade of Finnish fans caught up to a parade of Russians marching their way to the match. According to police, both nationalities threw flares and bottles at each other.
"Both groups provoked each other, and someone always gets irate," says Helsinki police spokesman Juha Hänninen.
Police were also targeted by the rioters. They estimate that around 4,000 people took part in the parades and that as many as 8,000 Russians may have attended the match -- the largest contingent of foreign football fans ever to attend a match in Finland.
The afternoon before the match was mostly peaceful, with a busy carnival atmosphere. Russian fans hung flags out of their car windows and drove around town honking.