A violent anti-migrant mob clashed with police on Sunday, but it was the migrants themselves, not the rioters, against whom security forces took action.

According to TIME Magazine, leaders of the mob called for the purging of minorities and migrants in the country, allegedly in response to the murder of a Russian man, Yegor Shcherbakov, last week—allegedly by a migrant worker who was not ethnically Russian.

Moscow Mayor Sergei Sobyanin denounced the mob’s tactics, but did not act against them. Instead of promising he would rebuild and/or protect the vegetable warehouse the mob had attacked, he ordered it to be closed down on the basis of its use of migrant labor, and delayed illegal migrants at the warehouse. The Wall Street Journal reports that Russian police took more than 1,000 people into custody to check their migrant status, and authorities promised they would take similar action at other places in the city known to use migrant labor.

Such violence between ethnic minorities in Russia and ethnic Russians themselves are nothing new for the country—there were similar riots in 2010 when another Russian man was killed by a man from the Caucuses.