The raid is one of two launched by police this month in an attempt to find the instigators of a Sept. 14 violent altercation involving 50 migrants in St. Petersburg’s market area, the city’s Fontanka news website reported. St. Petersburg police said it inspected a total of 841 foreigners’ documents in the raids, bringing 130 of them to police stations to face administrative charges.

Police in St. Petersburg rounded up more than 800 migrant workers in a market raid last week following a mass brawl, the local 47news.ru news website reported Monday.

Friday’s roundup of 800 migrant workers involved 250 police officers, FSB, anti-riot police and other special agents. More than 20 migrants are set to be deported following the mass raids, according to 47news.

The first searches on Oct. 11 involved around 70 law enforcement officials and resulted in the detention of 43 foreign nationals. Fontanka reported at the time that some of the migrant workers were due to be deported.

The outlet reported that police have one of the main instigators of the Sept. 14 brawl, a national of the ex-Soviet Central Asian state of Tajikistan, in custody. Authorities are now looking for three more Tajik nationals, one of whom 47news reported may have fled Russia.