Police have released surveillance video they said shows Occupy demonstrators breaking into City Hall during the protests in Oakland Saturday night.
Oakland police spokeswoman Cynthia Perkins said the protesters were able to get inside the building using what she termed a "pry tool." Once the protesters were inside, police said they removed items including an American Flag.
The start of the black-and-white video shows people coming through the door, then papers being strewn about.
Images from a second camera show a crowd of people on the front stairs, with the American flag being set on fire.
"This type of criminal behavior, clearly outside of the First Amendment, is disrespectful to the residents of Oakland and is unacceptable and will not be tolerated in my City," said newly appointed Police Chief Howard Jordan.
"The residents of the City deserve better than this, and it's time for the violence and vandalism to cease," he said.
In releasing the images Wednesday, Oakland police investigators asked members of the public to call police if they recognize people in the crowd.
More than 400 people were arrested Saturday when a midday march escalated into a clash between some rock-throwing protesters and police who responded with tear gas.