The first signs of violence: Protesters broke shop windows in downtown Washington. A Bank of America branch had all its windows shattered, and a Starbucks was left with a gaping hole in its glass front door.

Police in riot helmets moved in quickly, using pepper spray to break up groups of protesters, who spread out and kept breaking windows. What exactly they were protesting was not clear – a witness said they saw a lot of black anarchist symbols, and most of protesters appeared to be young men.