Updated at 1:30 p.m. ET
Russian police arrested opposition leader Alexei Navalny outside his home Monday, preventing the man who organized nationwide demonstrations against Russian President Vladimir Putin from joining a rally in Moscow.
Thousands of protesters turned out anyway, and dozens of detentions were reported in both Moscow and St. Petersburg.
"Alexei was detained at the entrance of the house," his wife, Julia Bulk, wrote on Navalny's Twitter feed. She posted a photo showing police taking her husband to a police vehicle, captioning the photo, "Russia Day!"
Other images from the day show thousands of demonstrators in St. Petersburg chanting slogans against Putin — and black-clad police marching through the crowd, making arrests and pulling people off of monuments.
Some 500 people were detained in St. Petersburg, Interfax reports, citing police. In Moscow, more than 150 were detained in the city's downtown "for violating public order," says state-run Tass media.
Police say Navalny was detained for breaking laws regarding public meetings and obeying authorities, the Interfax news agency reports. It adds that the opposition leader ran into problems setting up a planned demonstration on Sakharov Avenue, and instead told his allies on Sunday to gather on Tverskaya Street.
Navalny, an opposition leader who was also arrested for organizing large anti-Putin protests in March, had called for national demonstrations on the holiday that marks Russia's formal emergence from the Soviet era in 1990. He's hoping to challenge Putin in next year's presidential election, delivering speeches around the country, as NPR's Lucian Kim reported last week.
The center of the Moscow protest is at Pushkin Square — and while NPR's Mary Louise Kelly says the crowd there is huge, she adds that it's also difficult to ascertain how many people are there for Navalny's cause, and how many for the national holiday.
"There are people walking around the streets in World War I uniforms," Mary Louise says. "There are big stages set up for concerts."
She adds that while the mood in the square had seemed peaceful earlier Monday, "the situation is changing very quickly" with "images streaming in of police and protesters pushing toward one another" as bystanders struggle to get out of the way.
The arrests began, Mary Louise says, after the crowd began chanting — something the authorities had warned them not to do.
Here's how The Moscow Times described the scene:
"An hour after the rally started, police started separating the crowd into groups and then isolating them from each other — a tactic known as "kettling." Several journalists ended up inside these 'kettles.' "Detentions increased as police pushed back on the crowd. " 'They were pushing so hard that I thought they could break my neighbor's bones,' Anna, 23, said after the rally. 'Many were crying, people were hysterical.' "
From images that we're seeing, many young people were among the protesters — and many were detained. After opposition activist Ilya Yashin, 33, was detained and put in a police bus, he tweeted an image from inside, showing himself with a half-dozen youths in Moscow.
And in St. Petersburg, several teenage girls were arrested, as Financial Times journalist Max Seddon tweeted.
"I am glad that the protest movement is getting younger," Yashin said in a posting that showed a young woman next to riot police late Monday. It was an answer, he added, to those who complain Russia has no future.
An unlikely object of dispute emerged at the St. Petersburg demonstration: As Russian journalist Arseny Vesnin and others noted, a giant yellow duck was among those detained by police, after being batted around in the air by the crowd.
By making an appearance, the duck was reprising its role in the large March protests. It's a reference to a report by Navalny's Anti-Corruption Foundation from last fall, which said that a vacation estate frequented by Prime Minister Dmitry Medvedev has a special house just for ducks.
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