Prosecutors in Minnesota filed new charges Wednesday against the four former Minneapolis police officers present when George Floyd died in custody, as protesters returned to the streets of American cities, but a relatively calm tone prevailed early in the evening.

The charge against Derek Chauvin — the officer who knelt on Floyd’s neck until he lost consciousness — was upgraded to second-degree murder from third-degree, Minnesota Attorney General Keith Ellison (D) announced. The other three officers, who restrained Floyd or stood guard while passersby pleaded for Chauvin to stop, were charged with aiding and abetting the murder.

Those charges — which an attorney for Floyd’s family called “a source of peace” — came on a day when peace seemed to be making a comeback, at least tentatively. After a week of aggressive use of force by police amid looting and vandalism in some cities, the tone changed. Police in many cities hung back and even marched with demonstrators, while protesters expelled vandals themselves.

But if the cycle of protester anger and police reaction simmered down somewhat, the District was an exception.

Federal officials sent a small army of National Guardsmen and federal law enforcement officers into downtown streets. The security perimeter around the White House was expanded to include the area where protesters had been forcibly removed on Monday to clear the way for President Trump to visit a fire-damaged church.

The church, and the street, were now off-limits. Federal prison guards stood watch near the White House, looking over their riot shields at hot, quiet, mostly empty streets. A crowd gathered near Trump’s D.C. hotel instead, mounting a peaceful demonstration.

Thousands gathered near the White House, and the crowd fell silent as somebody played Sam Cooke’s “A Change Is Gonna Come,” a 1964 song that became an anthem of the civil rights era.

Some of the active-duty soldiers flown to the Washington area earlier this week had been scheduled to return home Wednesday, but Defense Secretary Mark T. Esper canceled that order and kept them in reserve at bases outside Washington, as first reported by the Associated Press.

Still, Esper said Wednesday that he did not support the use of the Insurrection Act to respond to the unrest caused by the Floyd’s death. That law permits the president to use active-duty troops on American streets to bolster security, something Trump had suggested he might do if necessary.

D.C. Mayor Muriel E. Bowser (D) said city officials were not even aware which federal agencies had sent officers to Washington.

“They are under their control, not ours,” Bowser said.

When the protests erupted last week, they were focused sharply on police brutality. But since then, Trump’s reaction — calling for more aggressiveness and “domination” against the protesters, describing some as “thugs,” using force on peaceful protesters to clear his own path to the photo op — has made him a target of criticism at home and abroad.

On Wednesday, former defense secretary Jim Mattis issued a statement condemning Trump, saying he “does not even pretend to try” to unite Americans in a time of crisis.

“I swore an oath to support and defend the Constitution,” Mattis wrote, in his first major statement about the president since resigning as Trump’s defense secretary in late 2018. “Never did I dream that troops taking that same oath would be ordered under any circumstance to violate the constitutional rights of their fellow citizens.”

Gen. Mark A. Milley, chairman of the Joint Chiefs of Staff, sent a memo to U.S. military commanders reminding them that the Constitution protects freedom of speech and peaceful assembly. “We in uniform — all branches, all components, and all ranks — remain committed to our national values and principles embedded in the Constitution,” Milley wrote.

The memo was notable not for its sentiments, since all military members swear an oath to the Constitution, but for its timing, coming at a moment when Trump and his allies have called for the military to crack down on demonstrators.

Trump made no public appearances Wednesday. Instead, he took to Twitter to tout his efforts to help African Americans during his presidency and to issue a terse call for “LAW & ORDER!”

In its early hours, Wednesday night was relatively peaceful — with some exceptions. In Huntsville, Ala., police fired gas at protesters, scattering a crowd and leaving a toddler-age girl crying, according to the news site al.com. In Brooklyn, video shot by reporters showed skirmishes between protesters and police. In Newport Beach, Calif., a man was arrested after plowing his car through a group of protesters, though no one was seriously injured.

But many protests were uneventful. In West Hollywood, Calif., a gay pride parade was supplemented by a civil rights march, with hundreds of people wearing rainbow attire and carrying signs against police brutality.

In Philadelphia, a large march broke up peacefully after the city’s 6 p.m. curfew, as a protest leader, Sixx King, led more than a thousand kneeling demonstrators in prayer.

“We’ll be out here tomorrow,” he promised the crowd, then led them in a chant: “When? Every day!”

In at least two cities on Wednesday, the protests triggered changes that promised to alter their very landscape.

In Philadelphia, a crane removed a prominent statue of former mayor Frank Rizzo, a tough-on-crime politician whose tenure brought complaints of police brutality. In Richmond, Virginia Gov. Ralph Northam (D) said he is planning to remove a statue of Confederate General Robert E. Lee from its place on the city’s Monument Avenue, a once-unthinkable change in the Confederacy’s old capital.

Both statues had been targeted by protesters and tagged with graffiti. In recent days, the city of Alexandria, Va., had removed a statue of a Confederate soldier, and Birmingham, Ala., removed a five-story-tall Confederate monument.

In Minneapolis, Floyd’s son Quincy Mason Floyd, 27, visited the site of his father’s death for the first time. “No man or woman should be without their father,” Floyd said.

A report by the county medical examiner released Wednesday found that Floyd had tested positive for the coronavirus in April but was asymptomatic at the time of his death. It also found “blunt force injuries” to Floyd’s forehead, face, upper lip, shoulders, hands, elbows and legs.

One Minneapolis city council member said he was considering a far-reaching response: abolishing the city’s police department and starting over.

“I don’t know yet, though several of us on the council are working on finding out, what it would take to disband the MPD and start fresh with a community-oriented, nonviolent public safety and outreach capacity,” council member Steve Fletcher wrote in a Twitter thread.

That idea remains, for now, just an idea: The council has not even begun to sketch out what would replace the current police department, or how it would be different.

In Washington, Justice Department officials said the massive law enforcement presence has been orchestrated by Attorney General William P. Barr, who wanted to “flood the zone” after incidents of vandalism in the early days of the protests.

But the officers have kept coming even after protests became more peaceful, and changes made Wednesday brought the officers and the protesters much closer together. On Tuesday, the crowds and the officers were separated by a fence and an expanse of open space; by Wednesday, the officers came out from behind the fence and stood in the street with riot gear.

Experts on crowd control have said that violates long-held ideas about how to handle crowds, which teach that the first goal should be de-escalation and that heavy-handed policing often backfires.

“The heavy hand is a smack in the face, and the danger is that it may make things worse,” said Dennis Kenney, a professor at John Jay College in New York with expertise in police response to protests. “It really does communicate something about where those who are in charge think our society sits right now. We’re in the process of demonstrating to the people who are out in the streets that they are right to be there.”

Katie Mettler, Devlin Barrett, Gregory Schneider and Dan Lamothe contributed to this report.