OAKLAND (AP) — Police have released surveillance video they say shows Occupy demonstrators breaking into City Hall during the protests in Oakland Saturday night.

Protesters had claimed the door was unlocked.

Oakland police spokeswoman Cynthia Perkins says the protesters were able to get inside the building using what she termed a “pry tool.” Once the protesters were inside, police say 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.

In releasing the images, Oakland police investigators are asking 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.