The supporters of Dinamo Zagreb and Hajduk Split fought each other with baseball bats and iron bars Wednesday on the highway linking Zagreb with Split on the Adriatic coast.
Police say they were travelling in vans in the opposite direction when the encounter occurred. The motive of the fight between the fans of the two biggest rival clubs in Croatia was not immediately clear, but such clashes have often happened in the past.
Police say several participants were arrested and several vehicles they were travelling in were demolished during the clash.