Protests turned violent in Germany ahead of the G-20 summit.
The G-20 summit is a meeting between the leaders of 20 of the world's largest economies. This year, they're expected to discuss climate change, trade and security threats, among other issues.
Thursday evening, police and anti-capitalist protesters clashed in the streets of Hamburg, Germany, after police ordered activists to remove their masks.
Protesters began throwing rocks and bottles when security forces tried to separate far-left "black bloc" protesters from the rest of the group. Police fired water cannons into the crowd.
Organizers canceled the event after the violence broke out. Some protesters left, but over 4,000 stayed. The protest continued until around midnight local time.
Police don't have a full tally of how many people were arrested but said that dozens of officers were injured.