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Dozens of football fans, believed to be Russian, have attacked four stewards following the team's opening European Championship match in Poland.
Amateur footage showed supporters punching and kicking the volunteers - including one lying on the ground after being injured.
The violence erupted in the concourse area of Wroclaw Municipal Stadium, after Russia's 4-1 win against Czech Republic.
Four officials were taken to hospital after the clashes, but none were badly injured, police spokesman Pawel Petrykowski said.
The beatings lasted for a "few dynamic minutes," he said, adding that it was a "small incident".
No arrests were made but police said they were examining security footage in an attempt to identify the attackers.
The video was uploaded onto the internet by a user called 'Oleksiak'.
He said the fans became aggressive after a steward identified one as a person who had thrown what was thought to be a flare.
European football's governing body Uefa said it was aware of a "brief and isolated incident" involving around 30 fans.
"The situation was quickly and efficiently brought under control," a Uefa statement said.
"The cause of the incident is not currently known but we are studying the security reports and available images.
"Uefa remains entirely committed to the safety and security of all fans and spectators at all matches of Euro 2012."
The attacks followed the arrest of four other Russian supporters, who had allegedly started a fight in a bar in Wroclaw's old town.
There was also controversy on Thursday, when racist incidents occurred as the Dutch team trained in Krakow.
The football tournament began on Friday, with a colourful opening ceremony in Poland.
England's first match, against France in Donetsk in Ukraine, takes place on Monday.
