Police fired tear gas against demonstrators taking part in a protest Wednesday before a match between hosts Brazil and Mexico in football's Confederations Cup in Fortaleza, dpa quoted witnesses as saying. Police intervened after some demonstrators threw stones during the protest, which began peacefully several hours before kick-off. Witnesses said several people were injured. An estimated 10,000 people took part in the protests in the north-eastern city. Protests were also planned Thursday in Rio de Janeiro where world champions Spain are scheduled to play Tahiti in the Confederations Cup tournament. Mass protests have been taking place in Brazil this week over poor public services, high prices and corruption, as well as against the cost of staging the 2014 World Cup.