Crowds of Trump supporters protested into the night in Washington, D.C., Saturday to highlight unsubstantiated claims of voter fraud in the Nov. 3 election and falsely assert that President Trump defeated President-elect Joe Biden.The state of play: The situation became tense in the evening after some 300 counter-protesters also rallied in D.C., the Washington Post reports. By 8 p.m. scuffles broke out between the two sides and police arrested at least 10 people, per WashPost.In the morning, Trump waved at supporters as his motorcade drove through D.C. toward his private golf club in Sterling, Va., per the New York Times.Why it matters: Trump has not publicly conceded to Biden and is pursuing lawsuits in several states with baseless voter fraud claims, despite his own Department of Homeland Security calling the election "the most secure in American history."What they're saying: Mayor Muriel Bowser said D.C. approves of "peaceful First Amendment demonstrations," but cautioned out-of-towners who planned to carry firearms to the nation's capital that the city has strict gun laws, per the Post.In photos: Police move to keep Trump supporters and counter-protesters apart in Black Lives Matter Plaza. Photo: Andrew Caballero-Reynolds/AFP via Getty Images Trump supporters and counter-protesters face off in D.C. Photo: Andrew Caballero-Reynolds/AFP via Getty Images An anti-Trump demonstrator argues with a pro-Trump supporter argues at Black Lives Matter Plaza. Photo: Andrew Caballero-Reynolds/AFP via Getty Images Trump supporters during the D.C. rally. Photo: Olivier Douliery/AFP via Getty Images Thousands of Trump supporters have rallied in D.C., AP notes. Photo: Olivier Douliery/AFP via Getty Images Trump supporters cheer on the president's motorcade. Photo: Mandel Ngan/AFP via Getty Images Trump supporters cheering at the president's motorcade as it passes by Freedom Plaza. Photo: Mandel Ngan/AFP via Getty Images The daytime demonstration was largely peaceful, AP and WashPost note. Photo: Olivier Douliery/AFP via Getty Images Ahead of the rally, police shut down parts of downtown D.C., "where many stores and offices have been boarded up since Election Day," AP reports. Photo: Andrew Caballero-Reynolds/AFP via Getty ImagesEditor's note: This article has been updated with the latest protest developments and more photos.