A car passenger holds a sign protesting President Donald Trump during a "No Kings" rally on Saturday in Whittier, Calif. (AP photo)

PHILADELPHIA — Masses of demonstrators packed into streets, parks and plazas across the United States on Saturday to protest President Donald Trump, marching through downtowns and small towns, blaring anti-authoritarian chants mixed with support for protecting democracy and immigrant rights.

Organizers of the “No Kings” demonstrations said millions had marched in hundreds of events. Governors across the U.S. had urged calm and vowed no tolerance for violence, while some mobilized the National Guard ahead of marchers gathering.

Confrontations were isolated. But police in Los Angeles, where protests over federal immigration enforcement raids erupted a week earlier and sparked demonstrations across the country, used tear gas and crowd-control munitions to clear out protesters after the formal event ended. Officers in Portland also fired tear gas and projectiles to disperse a crowd that protested in front of a U.S. Immigration and Customs Enforcement building well into the evening.

And in Salt Lake City, Utah, police were investigating a shooting during a march downtown that left one person critically injured. Three people were taken into custody, including a man believed to be the shooter, who also suffered a gunshot wound, according to Police Chief Brian Redd.

Redd said it was too early to tell if the shooting was politically motivated and whether those involved knew each other. The shooter appeared to be walking alongside the group of thousands who were marching, he added. Video feeds showed demonstrators running for safety as gunshots rang out.

Huge, boisterous crowds marched, danced, drummed, and chanted shoulder-to-shoulder in New York, Denver, Chicago, Austin and Los Angeles, some behind “no kings” banners. Atlanta’s 5,000-capacity event quickly reached its limit, with thousands more gathered outside barriers to hear speakers in front of the state Capitol. Officials in Seattle estimated that more than 70,000 people attended the city’s largest rally downtown, the Seattle Times reported.

Trump was in Washington for a military parade marking the Army’s 250th anniversary that coincides with the president’s birthday. About 200 protesters assembled in northwest Washington’s Logan Circle and chanted “Trump must go now” before erupting in cheers. A larger-than-life puppet of Trump — a caricature of the president wearing a crown and sitting on a golden toilet — was wheeled through the crowd.

In some places, organizers handed out little American flags while others flew their flags upside down, a sign of distress. Mexican flags, which have become a fixture of the Los Angeles protests against immigration raids, also made an appearance at some demonstrations Saturday.

In Culpepper, Virginia, police said one person was struck by an SUV when a 21-year-old driver intentionally accelerated his SUV into the crowd as protesters were leaving a rally. The driver was charged with reckless driving.

The demonstrations come on the heels of the protests over the federal immigration enforcement raids that began last week and Trump ordering the National Guard and Marines to Los Angeles, where protesters blocked a freeway and set cars on fire.

“Today, across red states and blue, rural towns and major cities, Americans stood in peaceful unity and made it clear: we don’t do kings,” the No Kings Coalition said in a statement Saturday afternoon after many events had ended.

Los Angeles

Thousands gathered in front of City Hall, waving signs and listening to a Native American drum circle before marching through the streets.

As protesters passed National Guard troops or U.S. Marines stationed at various buildings, most interactions were friendly, with demonstrators giving fist bumps or posing for selfies. But others chanted “shame” or “go home” at the troops.

Amid signs reading “They fear us don’t back down California” and “We carry dreams not danger, “ one demonstrator carried a 2-foot-tall Trump pinata on a stick, with a crown on his head and sombrero hanging off his back. Another hoisted a huge helium-filled orange baby balloon with blond hair styled like Trump’s.

A few blocks from City Hall, protesters gathered in front of the downtown federal detention center being guarded by a line of Marines and other law enforcement. It was the first time that the Marines, in combat gear and holding rifles, have appeared at a demonstration since they were deployed to city on Friday with the stated mission of defending federal property.

New York City

Marchers in the crowd that stretched for blocks along Fifth Avenue had diverse reasons for coming, including anger over Trump’s immigration policies, support for the Palestinian people and outrage over what they said was an erosion of free speech rights.

But there were patriotic symbols, too. Leah Griswold, 32, and Amber Laree, 59, who marched in suffragette white dresses, brought 250 American flags to hand out to people in the crowd.

“Our mothers who came out, fought for our rights, and now we’re fighting for future generations as well,” Griswold said.

Some protesters held signs denouncing Trump while others banged drums.

“We’re here because we’re worried about the existential crisis of this country and the planet and our species,” said Sean Kryston, 28.