Navalny had called for nationwide protests after publishing an investigation earlier this month alleging mass corruption charges against Medvedev, whose large fortune far exceeded his position’s salary.

At least 500 demonstrators were arrested in Moscow, reporter Charles Maynes tells NPR, among the tens of thousands who turned out nationwide — despite warnings from authorities that protesters would face fines and arrest for taking part in the illegal protest.

“There were reports of 2,000 people showing up in Nova Sibersk in Siberia, we had 10,000 in St. Petersburg, the estimates here in Moscow are about 20,000,” he says.

But Navalny saw little of the protest he organized. Maynes says “Riot police detained the opposition leader as soon as he arrived in downtown Moscow, with Navalny supporters briefly attempting to pry open the police van that held him,” in the capital’s iconic Pushkin Square.