A fight broke out in Irkutsk between a group of students who were taking part in a St. Patrick's Day flashmob and youths who misinterpreted the event as a pro-gay celebration.
Students and teachers at Easy School, an English language school, dressed in green and participated in a flashmob on Sunday at the Siberian city's Fashion Quarter mall, where a band performed for the merrymakers.
St. Patrick's Day is not widely observed in Russia, though it has gained popularity in recent times as a green-hued secular holiday.
About 15 people participated in the fight between the flashmobbers and "representatives of working youth," a regional police spokesman told Interfax. The attackers concluded that the flashmob members were of a "non-traditional sexual orientation" based on their outfits, which included kilts, the spokesman said.
A teacher at Easy School suffered a mild concussion as a result of the scuffle.
Police have already questioned eight participants in the fight, the spokesman said.
Witnesses said that the mall's security guards did not intervene in the fracas, local news source Irk.ru reported.
Gay activists have said that a law passed by the State Duma last year banning the dissemination of "gay propaganda" to minors has led to an increase in homophobia and violence toward sexual minorities.