Scores of bare-chested skinheads have reportedly attacked a crowd of about 3,000 people at a rock concert in central Russia, beating them with clubs.
Dozens of people were left bloodied and dazed by the attack, television and news agencies reported, and a news channel said a 14-year-old girl was killed at the concert in Miass, 900 miles east of Moscow.
Fourteen ambulances were called to the scene, witnesses said.
The motive for the attack was not known.
Many of Russia's top rock acts were attending the Tornado rock festival, the agency said.
Russia has an ingrained neo-Nazi skinhead movement. Racist attacks in Moscow and St Petersburg have been relatively common in recent years.
The January 2009 murder of lawyer Stanislav Markelov and journalist Anastasiya Baburova prompted a Kremlin crackdown on ultranationalists, who were blamed for the killings.
In April, a Moscow court banned the far-right Slavic Union, whose Russian acronym SS intentionally mimicked that used by the Nazis' infamous paramilitaries.
The group was declared extremist and shut down. Then the group's leader, Dmitry Demushkin, has said it tried to promote its far-right agenda legally and warned that the ban would enrage and embolden Russia's most radical ultranationalists.
Russia's ultranationalist movement is so deeply embedded in the country's culture that militant groups have sprouted up around Russia to fight it. Anti-racist groups regularly spearhead attacks on ultranationalists, sparking revenge assaults in an intensifying clash of ideologies.