MOSCOW, July 30 (RIA Novosti) – Moscow police had rounded up almost five hundred suspects in the city’s market places by Tuesday morning following an attack on the weekend on a police officer trying to detain a suspected sex offender at a food market.

“Over 470 people have been detained,” a police spokesperson told RIA Novosti Tuesday morning.

On Saturday, a team of police officers was attacked by a crowd of 20 to 25 people at the Matveyevsky food market in western Moscow as they were detaining a man suspected of sexually assaulting a 15-year-old girl.

One of the officers received serious head injuries after reportedly being hit with brass knuckles. The incident has been widely reported in the Russian media after an eyewitness video of the incident later went viral on social networks.

In a massive responsive to the attack, Moscow police launched an operation to check people working at city markets for complicity in crimes and offenses.

Earlier Monday, law enforcement officials reported they had already rounded up 300 people during the raids. The sweeping checks of market places continued, despite the fact that the suspected attacker who the police were originally looking for, named as Magomed Rasulov, had already been detained Monday while he was trying to flee the capital on a bus, the police said.

The attack has fueled ethnic tensions in the capital, whose marketplaces employ many migrants from post-Soviet states and representatives of ethnic minorities from Russia’s Muslim-populated North Caucasus regions, who are often treated as migrants in Moscow.

Russia introduced a law in 2007 banning foreign nationals from working in retail markets and shops, in what the government said was a bid to clamp down on the shadow economy.