There were fierce clashes between anti-G20 protesters and the police, and the situation was considered too volatile to allow US First Lady Melania Trump to attend a tour with the other G20 spouses.
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Far-left extremists threw rocks, set light to barricades and looted shops. Hamburg's police described the situation as "very serious".
AFP
It is thought there are about 100,000 anti-G20 protesters in Hamburg - but only a small proportion are taking part in the violence.
AFP
About 20,000 officers are on duty over the course of the G20.
Reuters
Protesters have set cars alight, smashed windows and fired flares at police helicopters.
AFP
They are protesting about a range of issues, including climate change, global wealth inequalities and the presence of Donald Trump and Vladimir Putin at the summit.
AFP
Police have been using water cannons to disperse protesters and put out the fires.
Reuters
German Chancellor Angela Merkel condemned the violence, saying it was "unacceptable" to "put peoples' lives in danger, put the protesters' own lives in danger".
Reuters
Friday night's protests were the latest in a series of demonstrations which began before the world leaders had even arrived.
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