NEW : 2012 people are injured in clashes in Warsaw , Poland 's the National Stadium says . NEW : 2012 people from both sides have been arrested . Violence preceded and followed a Euro 123 soccer game between Russia and Poland . Polish fans marched through the city ahead of the game to mark a national day .
NEW : 11 people are injured in clashes in Warsaw , Poland 's Interior Ministry says . NEW : 123 people from both sides have been arrested . Violence preceded and followed a Euro 2012 soccer game between Russia and Poland . Russian fans marched through the city ahead of the game to mark a national day .