(Newser) – Russian police today raided a vegetable warehouse, just a day after that warehouse became the target of the biggest anti-migrant unrest to hit the country in years. A riot broke out yesterday after the killing of a young man was blamed on a migrant from Russia's North Caucasus region, the BBC reports. Around 400 people were arrested after a crowd of thousands chanting "White power" and "Russia for the Russians" attacked a shopping center popular with migrant workers. The mob later attacked the vegetable warehouse that employs many workers from the Caucasus, believing the killer to be among those employees.

Police arrested more than 1,200 of the warehouse's employees, in what it called a "preemptive raid," the AP reports. Police said they suspected some of the detainees of having criminal connections, and said they'd found a car full of cash and unlicensed guns on the premises. Anti-migrant sentiment has long been stewing in Moscow. "It's simply impossible to live here. There are fights all the time," one resident tells Reuters. "The people working in this warehouse are no good—I'm sure there are criminals hiding among them."