Disorder has broken out in Washington DC amid tight security ahead of Donald Trump's inauguration.
A group of masked protesters, some carrying flags bearing the anarchist symbol, were filmed smashing windows, running through the streets and clashing with police.
One man dressed in black smashed the window of a McDonald's with a hammer, while others tipped over bins around an hour before the start of Mr Trump's ceremony.
A Bank of America branch and a Starbucks were among the other buildings targeted. Some were armed with bats and long wooden poles and there were unconfirmed reports of looting.
Police responded with tear gas, pepper spray, stun grenades and water cannon to disperse the protesters, who fled away from lines of officers.
Police cordoned off a crowd of around 100 demonstrators who chanted “hands up, don't shoot", as a helicopter hovered overhead.
Supporters shouted "let them go" amid fears of mass arrests.
Reporters at the scene said protesters attempted to break lines of police wearing full riot gear and wielding batons, but were pushed back by pepper spray and stun grenades.
Observers said the disorder appeared to be organised, with the black-clad group splitting from a larger protest before launching the wave of vandalism.
Police detained about 50 people and said they had charged numerous people with rioting. The group of detainees became a flash point after Mr Trump was sworn in, when a crowd of several hundred that had formed to call for their release turned violent, with some throwing bottles and rocks at police who responded with tear gas and stun grenades.
Two police officers sustained minor injuries from people who were trying to avoid arrest, police said.
Some groups had vowed to disrupt the inauguration ceremony, with members of #disruptj20 attempting to block ticket holders from entering the venue at security checkpoints.
At one checkpoint, protesters wore orange jumpsuits with black hoods over their faces to represent prisoners in US detention at Guantanamo Bay, which Barack Obama pledged to close.
Black Lives Matter and feminist groups also made their voices heard. Outside the International Spy Museum, protesters in Russian hats marched with signs calling Mr Trump “Putin's Puppet” and “Kremlin employee of the month".
Most Trump supporters walking to the inauguration past Union Station ignored protesters outside the railway station, but some shouted back and argued with demonstrators.
“Get a job,” shouted Doug Rahm, a Bikers for Trump member from Philadelphia. “Stop crying snowflakes, Trump won.”
One group stationed themselves in Washington offering out 4,200 free joints to campaign for the legalisation of cannabis, while the Answer Coalition demonstrated at the US Navy Memorial and in Freedom Plaza, near the White House.
A group calling itself Occupy Inauguration rallied at Meridian Hill Park and film-maker Michael Moore was to speak at an event in Washington's McPherson Square.
Outgoing homeland security secretary Jeh Johnson said 28,000 officials were being deployed for the security operation in Washington, including more than 3,000 police officers and 5,000 members of the National Guard.
The clashes came as Mr Trump was due to make his way to the US Capital to be sworn in as US President.
"It all begins today!" he tweeted on Friday morning. "The movement continues - the work begins."
Thousands of people have been protesting against his inauguration around the world, with activists hanging banners along the River Thames in London as part of the #bridgesnotwalls movement.
Additional reporting by AP
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