Thousands of people marched through central Moscow Sunday, chanting angry slogans, such as "Putin out!" and "Putin is Russia's shame", on the eve of Vladimir Putin's inauguration for an unprecedented third term as Russia's president.

ended in violence and hundreds of arrests as heavily-armored, tear gas-firing riot police moved in on a contingent of protesters who were attempting to cross a bridge that police had barricaded.

The crowd of 20,000 was far larger than either organizers or police had anticipated; last week authorities granted a permit for just 5,000 participants.