The skirmish followed an hour-long standoff on a street that runs alongside Hamburg’s downtown harbor. Thousands of protesters were gathered, and some began lobbing glass bottles and other objects as police rushed a group of “black bloc” activists huddled in the middle of the street. They were dressed in dark clothes with their faces concealed and carried signs condemning the state and promising, “Welcome to hell.”

https://www.washingtonpost.com/world/europe/hamburg-braces-for-mass-protests-asg-20-makes-the-city-a-siteof-global-discord/2017/07/05/afafae46-6044-11e7-80a2-8c226031ac3f_story.html