Dozens of police officers were injured as G20 protests turned violent in Hamburg.
Thousands of demonstrators have been in the German city since Tuesday when they descended for their 'Welcome to hell' protest.
Things started peacefully, but riot police used pepper spray and water cannon as some of the crowd became violent as darkness fell.
Seventy-six officers were injured in clashes on Thursday night, including three who were taken to hospital.
The pilots of a police helicopter sustained eye injuries when lasers were pointed at them, police said.
Officers moved in when thousands including a large 'black bloc' using masks to hide their identities moved to begin a march through the city.
Some anti-capitalists responded by throwing missiles including bottles and stones at officers.
The situation in the city remains tense, and clashes were reported in several districts of the port city.
However, a large number of protesters were being allowed to continue to march towards the G20 venue.
World leaders including Donald Trump, Theresa May, Angela Merkel and Vladimir Putin will be at the summit on Friday and Saturday.
It will be notable as the first meeting between the US and Russian presidents since Mr Trump came to power in an election that allegedly was tainted by Russian interference.
In the weeks leading up to the summit, police cars have been burned and train lines have been sabotaged.
Authorities in Hamburg and the nearby city of Rostock have confiscated improvised weapons such as fire-extinguishers filled with flammable liquid, baseball bats and other items in several raids.