Supporters of U.S. President Donald Trump participate in a "Stop the Steal" protest after the 2020 U.S. presidential election was called for Democratic candidate Joe Biden, in Washington, Nov. 14, 2020.
Supporters of U.S. President Donald Trump participate in a "Stop the Steal" protest after the 2020 U.S. presidential election was called for Democratic candidate Joe Biden, in Washington, Nov. 14, 2020.

Police in Washington say they arrested 21 people in connection with pro-Trump demonstrations and clashes Saturday. 

Those arrested included a 26-year-old charged with setting off a commercial grade firework at several Trump supporters eating at a restaurant, and two people from the state of Georgia charged with openly carrying firearms. 

Several rallies were scheduled for the day, including a Million MAGA March, a Women for Trump event and a Stop the Steal demonstration, which leveled unproven claims of voter fraud in the presidential election.

WATCH: Mike O’Sullivan's report

President Donald Trump has refused to concede the presidential race to President-elect Joe Biden, citing irregularities in several swing states. State election officials have reported no serious irregularities with the vote that would affect the outcome of the race.   

About two hours before the pro-Trump rallies were scheduled to begin, Trump rode down Pennsylvania Avenue in a motorcade, smiling and waving at some of the demonstrators who had come to show support for the president.  

Supporters of President Donald Trump cheer alongside his presidential motorcade at Freedom Plaza near the White House in Washington, Nov. 14, 2020.

The motorcade then took Trump to his namesake golf course in nearby Northern Virginia for a round of golf. On his return to the White House, the president again drove by to cheers of supporters, Fox News reported.  

The rallies were promoted by conservative media personalities as well as white nationalists and had fueled plans of counterdemonstrations organized by anti-fascism and anti-racism groups. Some scuffles broke out.  

It is not clear how many people turned up in Washington, and the city’s police department does not estimate crowd sizes.