Dozens of people were left bloodied and dazed in the attack, television and news agencies reported, and state news channel Rossiya-24 said a 14-year-old girl was killed at the concert in Miass, 900 miles (1,400 kilometers) east of Moscow.
Fourteen ambulances were called to the scene, the channel said, citing witness accounts. The motive for the attack was not known, and authorities couldn't be reached for comment. The ITAR-Tass agency said local police had refused comment.
Many of Russia's top rock acts were attending the "Tornado" rock festival, the agency said.
Russia has an ingrained neo-Nazi skinhead movement. Attacks on dark-skinned foreigners 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 paramilitary. The group was declared extremist and shut down. Then the group's leader, Dmitry Demushkin, told The Associated Press 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.
Neo-Nazi and other ultranationalist groups mushroomed in Russia after the 1991 Soviet collapse. The influx of immigrant workers and two wars with Chechen separatists triggered xenophobia and a surge in hate crimes.
Racially motivated attacks, often targeting people from Caucasus and Central Asia, peaked in 2008, when 110 were killed and 487 wounded, an independent watchdog, Sova, said. The Moscow Bureau for Human Rights estimated that some 70,000 neo-Nazis were active in Russia - compared with a just few thousand in the early 1990s.