Violence has marred a day of protest in Washington after thousands turned out in a show of support for Donald Trump.
Twenty people were arrested and at least one stabbing was reported as Trump supporters clashed with counter protesters in Washington.
According to the Washington Post, the stabbing happened when a fight broke out between two large groups.
Two officers were injured and several firearms were also recovered by police during the protests.
Following the clashes, Mr Trump demanded that the city's police and mayor "do their job" and called the counter protesters "radical left Antifa scum".
The unrest came just hours after thousands of demonstrators marched towards Freedom Plaza near the White House in downtown DC before heading towards the US Supreme Court building.
There were concerns the "Million MAGA March", which was heavily promoted on social media, would spark conflict with anti-Trump protesters who have gathered near the White House in Black Lives Matter Plaza for weeks.
Police closed off large sections of downtown, where many shops and offices have been boarded up since election day.
Sky News correspondent Alistair Bunkall, who is at the scene, said there have been a few "running battles" overnight.
"There have been a few scuffles near to where some Trump supporters are staying. Police, a lot of them on bikes, have boxed up some of the demonstrators, most of them Antifa protesters who are against Donald Trump remaining in the White House, and have been pushing them backwards from the square.
"Police have it under control at the moment, barring the odd running battle, but it could be quite a long night."
Earlier, "Stop the steal!" and "We are the champions!" was chanted by the Million MAGA March crowd, which included members of the far-right Proud Boys group and Oath Keepers militia as they supported Mr Trump's bid to stay in power nearly two weeks after election day.
The president is persisting with his legal claims and complaints despite top government and industry officials declaring voting on 3 November and the following count went smoothly with no more than the usual minor issues.
Republican leaders in four critical states won by Joe Biden - Arizona, Michigan, Pennsylvania and Wisconsin - have said they will not participate in a legally dubious scheme to flip their state's electors to vote for Mr Trump.
On Friday, Mr Trump appeared close to acknowledging, for the first time, he had not won the election.
"This administration will not be going to a lockdown," he told a White House briefing on the pandemic.
"Hopefully the, uh, whatever happens in the future - who knows which administration it will be? I guess time will tell."
But his supporters in Washington and other cities were keen to stand behind his unsubstantiated claims of election fraud as he pushes ahead with several legal challenges to overturn Mr Biden's victory.
One demonstrator in DC told Sky News: "I think this is showing the world President Trump has so much support.
"We see the fraud that's going on in front of our eyes and we're just not going to let it happen."
As the marches started, Mr Biden told reporters during a bike ride with his wife and Secret Service agents in Delaware he was getting closer to forming a cabinet.
On Friday, the president-elect further solidified his victory after results showed him winning Georgia to give him 306 electoral college votes - far more than the 270 needed and comfortably above Mr Trump's 232.
The president has only spoken publicly a few times since the election but his motorcade slowly drove through DC on Saturday, drawing cheers from the crowd.
Some ran alongside his limousine as the crowd chanted "USA, USA", and "four more years", while many carried American flags and signs calling for recounts.
Mr Trump was then driven to his Virginia golf club where he has spent a lot of time since the election.