More than 20,000 young Russians on Thursday marched in Moscow streets to mark National Unity day, however the celebrations were marred by isolated incidents. Some 20 masked youngsters in dark uniforms broke into a cafe in mid-town Moscow and beat customers. Customers attempting to retaliate were shot by non-lethal handguns, RIA Novosti news agency quoted police officers as saying, adding that seven people had been hospitalized. According to Russia's Criminal Code, use of non-lethal guns in an assault is punishable by up to seven years in prison. Also on Thursday, major nationalists events took place in Moscow, Novosibirsk and other towns. Most of them were organized by the semi-official so-called Movement Against Illegal Migration (DPNI). Russia's official National Unity Day was introduced by the Kremlin in 2005 as the authorities' attempt to scrap the legacy of the communist Revolution Day used to celebrate the same week of November. By declaring Nov. 4 the Day of National Unity, authorities unwillingly unleashed grassroots nationalistic movements which use the occasion to stage race-hate motivated marches across the country. These marches are often accompanied with acts of mob violence against ethnic minorities. According to local media reports, about 6,000 police and interior troops had ensured security and rule of law in Moscow during the holiday's celebrations. Police said all the events passed without major problems. 