Anti-capitalism demonstrators, marching under banners that said "Smash the state," taunted police and attacked a McDonald's restaurant in Ottawa, Canada's capital.
As roughly 200 people protesting international financial meetings in Ottawa walked down a central thoroughfare, about a dozen youths used sticks and rocks to smash the windows of the restaurant, which was closed.
Police said they arrested four demonstrators for vandalism in connection with the McDonald's attack and for writing graffiti on buildings.
One local television journalist was injured in a melee.
The Group of 20 nations--created in 1999 to address international financial concerns--is meeting in Ottawa this weekend. Policy-making committees of the International Monetary Fund and the World Bank also are holding talks in the capital.