Donald Trump (Official White House photo)

WASHINGTON (AP) — Amid racial unrest across the nation, President Donald Trump on Monday declared himself “the president of law and order” and threatened to deploy the United States military to American cities to quell a rise of violent protests.

As Trump spoke, an incredible TV split screen developed around the White House. While he addressed the nation in the White House’s idyllic Rose Garden, a series of military vehicles rolled out front on Pennsylvania Avenue and military police and law enforcement clashed with protesters at Lafayette Park.

Those peaceful demonstrators were cleared so Trump could walk across the park to St. John’s Episcopal Church, known as “The Church of the Presidents,” which suffered fire damage in a protest this week. Holding a Bible, he then stood with several of his Cabinet members as the cameras clicked.

“We have the greatest country in the world,” Trump declared. “We’re going to keep it safe.”

Trump said he would mobilize “thousands and thousands” of soldiers to keep the peace if governors did not use the National Guard to shut down the protests. Loud tear gas explosions could be heard as authorities moved what appeared to be peaceful protests in the park. The escalation came just after Attorney General William Barr came to the park to survey the demonstrators.

According to senior defense officials, between 600 and 800 National Guard members from five states were being sent to Washington to provide assistance. Those troops were either already on the ground or will arrive by midnight.

Under the Civil War-era Posse Comitatus Act, federal troops are prohibited from performing domestic law enforcement actions such as making arrests, seizing property or searching people. In extreme cases, however, the president can invoke the Insurrection Act, also from the Civil War, which allows the use of active-duty or National Guard troops for law enforcement.

The officials said that some of the National Guard in D.C. will be armed and others will not. They said that the D.C. guard members do not have non-lethal weapons. The military police that are visible in the city are members of the Guard.

The competing messages — one conciliatory, one bellicose — came as the U.S. braced for another round of violence at a time when the country is already buckling because of the coronavirus outbreak and the Depression-level unemployment it has caused.

“We are a country that is scared. We are a country that is angry,” said Sam Page, county executive in St. Louis County, Missouri, where the city of Ferguson has been synonymous with the Black Lives Matter movement since the 2014 death of Michael Brown, a black 18-year-old, in a clash with a white officer. “And we are a country that is holding out for the promise of justice for all.”

In Minneapolis, Floyd’s brother, Terrence, made an emotional plea at the site where Floyd was pinned to the pavement by an officer who put his knee on the handcuffed black man’s neck until he stopped breathing.

“Let’s switch it up, y’all. Let’s switch it up. Do this peacefully, please,” Terrence Floyd said.

The crowd chanted, “What’s his name? George Floyd!” and “One down, three to go!” in reference to the four officers involved in Floyd’s arrest. Officer Derek Chauvin has been charged with murder, but protesters are demanding that his colleagues be prosecuted, too. All four were fired.

The gathering was part rally and part impromptu eulogy as Floyd urged people to stop the violence and use their power at the ballot box.

“If I’m not over here messing up my community, then what are you all doing?” he said. “You all are doing nothing. Because that’s not going to bring my brother back at all.”

Meanwhile, an autopsy commissioned for Floyd’s family found that he died of asphyxiation from neck and back compression, the family’s attorneys said.

That distinguishes it from the official autopsy, which said he died from the effects of being restrained along with underlying health problems and potential intoxicants in his system. The official autopsy found nothing “to support a diagnosis of traumatic asphyxia or strangulation.”

The second autopsy was done by a doctor who also examined the body of Eric Garner, a New York man who died in an officer’s chokehold six years ago.

Authorities in many cities have blamed the violence on outside agitators, though have provided little evidence to back that up.

But on Monday, federal authorities arrested a 28-year-old Illinois man, Matthew Lee Rupert, saying he had posted self-recorded video on his Facebook page last week that showed him in Minneapolis handing out explosive devices and encouraging people to throw them at law enforcement officers. The video also showed him attempting to light a business on fire, and looting, according to an FBI affidivit. Early Sunday, he posted more videos of himself in and around Chicago, saying “let’s start a riot.”

He was arrested in Chicago for violating the city’s curfew.

As they girded for more violence, Washington and New York joined other cities in announcing curfews. The move followed a chaotic Sunday night in New York, where groups broke into Chanel, Prada and Rolex boutiques and electronics stores.

Hours before Washington’s 7 p.m. curfew was to go into effect, nearly a dozen National Guard vehicles rumbled through the White House grounds and exited opposite Lafayette Park, where crowds had gathered for another night of protests. On Sunday, police fired tear gas and stun grenades into a crowd of protesters in the park. They scattered to light fires in nearby streets.

At least 4,400 people nationwide have been arrested over the past week for such offenses as stealing, blocking highways and breaking curfew, according to a count by The Associated Press.

Police officers and National Guard soldiers enforcing a curfew in Louisville, Kentucky, killed a man early Monday when they returned fire after someone in a large group shot at them, police said. In Indianapolis, two people were reported dead in bursts of downtown violence over the weekend, adding to deaths recorded in Detroit and Minneapolis.

While police in places tried to ease tensions by kneeling or marching in solidarity with the demonstrators, officers around the country were accused of treating protesters with the same kind of heavy-handed tactics that contributed to the unrest in the first place.

Cities struggled to keep police in line.

In Fort Lauderdale, Florida, an officer was suspended for pushing a kneeling woman to the ground during a protest. In Atlanta, two officers were fired after bashing in the window of a car and using a stun gun on the occupants. In Los Angeles, a police SUV accelerated into several protesters, knocking two people to the ground.

In New York, the police commissioner said about six incidents were being investigated by the department’s internal affairs bureau, including a weekend confrontation in Brooklyn in which two police vehicles appeared to plow through a group of protesters. In another incident, an officer pointed a gun at protesters, drawing condemnation from the mayor.

“I think some of the actions of the NYPD have exacerbated the anger,” New York Gov. Andrew Cuomo said. “There are videos of some NYPD actions that are very disturbing. There are videos of NYPD cars driving into a crowd that are very disturbing. Pulling a mask down off a person to pepper spray them. Throwing a woman to the ground. It’s on video! It’s on video!”