The clashes began Saturday when activists torched an American flag in front of City Hall before breaking into the historic building and damaging art exhibits inside. The protesters later marched to an empty convention center they wanted to convert into a social center and tore down fencing.

　　Police say the protesters threw rocks, bottles and other objects at officers who responded by firing tear gas and bean bag rounds (less lethal shotgun ammunition). Officials say three police officers and one protester were injured.

　　During a press conference Saturday, Mayor Jean Quan called on Occupy protesters to stop "using Oakland as its playground."  She blamed the destruction on a violent splinter group within the Occupy Oakland demonstration.

　　An estimated 1,000 people attended Saturday's march.

　　The national Occupy Wall Street movement began in New York in September. It says it represents the "99 percent" - those outside the top 1 percent of wealth holders.

　　Meanwhile, authorities in Washington, D.C., are planning to evict Occupy protesters from two parks where they have been camping since October.