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 when 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:

Editor's note: This article has been updated with the latest protest developments and more photos.