Racism has not been ruled out, most victims are Chinese and Vietnamese.
Three months ago, Novyie Izvestia wrote that many young people having come from Africa and Asia to study are ready to leave Russia forever unless law enforcement here starts taking their security seriously. Since then, a large number of students, paying considerable money for their education, have left the country. However, it turned out that federal authorities consider the problem exaggerated in the minds of the public, and do not intend to take special measures to protect foreign students.
Source: Racism in Russian - FEATURE - MOSNEWS.COM
More: BBC - Racism on the rise in Russia and Racism on the rise in Russia