In retaliation, the police utilized water cannons, pepper spray, and batons to disperse marchers. Police expected around 100,000 of them, including 8,000 whom security forces say are ready to commit violence.
Fires burned across Hamburg for a second day as police and protesters clashed while the leaders of the world's top economies met for the G20 summit.
All eyes will be on the United States president who will make his maiden appearance at the summit.
Violent protests have raged throughout the northern German city ahead of the worldwide conference, a gathering of the leaders of major economies. She said would be "bold" and show that Britain will keep its global influence after Brexit.
"Her communications director Stephanie Grisham told German media "Hamburg police couldn't provide clearance for us to leave", which "[is] unfortunate".
On Friday morning, Trump tweeted her concern for those injured in Hamburg.
Céline Bak, a climate policy and G20 expert who is a senior fellow at the Centre for International Governance Innovation, said the best case would be for Trump to at least sign on to Merkel's climate appendix.
Thousands are protesting capitalism, climate polices and globalization, among other issues.
Police claim one of their helicopters was attacked with a flare, and although the protests outside the summit itself are reported to be peaceful, officers have called in extra reinforcements to deal with the unrest, according to The Local.
Video from earlier in the two-day meeting captured Merkel delivering a clear eye roll while listening to Russian president Vladimir Putin. Trump had other priorities, however; he made headlines on Friday when he reportedly missed part of a G20 climate change session to meet with Putin, though he did take the floor at the session first.
Djokovic eases into third round
Dimitrov, a Wimbledon semifinalist in 2014, will next face either seven-time champion Roger Federer or Mischa Zverev . He will next play Ernests Gulbis , who produced some thrilling tennis to beat No29 seed Juan Martin del Potro .
Wayne Rooney closing in on Everton FC return
When Wayne Rooney lost a step or two, United shifted him to another position and then later a diminished role in the team. Manchester United are ready to waive a fee for Wayne Rooney as they look to smooth his departure from Old Trafford.