MINNEAPOLIS — Protesters set police cars ablaze, smashed businesses’ windows and skirmished with baton-wielding officers in streets from Atlanta to Los Angeles, as anger over George Floyd’s death spread across the country. Authorities were bracing for more violence Saturday, with some calling in the National Guard to beef up overwhelmed forces.

In Minneapolis, the city where Floyd died Monday after a white police officer pressed a knee into his neck and kept it there for more than eight minutes, Minnesota Gov. Tim Walz fully mobilized the state’s National Guard and promised a massive show of force to help quell unrest that has grown increasingly destructive.

“The situation in Minneapolis is no longer in any way about the murder of George Floyd,” Walz said. “It is about attacking civil society, instilling fear and disrupting our great cities.”

On Friday alone, racially diverse crowds took to the streets in more than two dozen cities — from New York to Oakland, California, from Atlanta to Portland, Oregon — for protests that typically began peacefully before many descended into violence.

At least two deaths were connected to the demonstrations; hundreds of people were arrested and police used batons, rubber bullets and pepper spray to push back crowds in some cities. Many departments reported officers were injured, while social media was awash in images of police using forceful tactics, throwing protesters to the ground, using bicycles as shields, and trampling a protester while on horseback.

Many protesters spoke of frustration that Floyd’s death was one more in a litany. It comes in the wake of the killing in Georgia of Ahmaud Arbery, who was shot after being pursued by two white men while running in their neighborhood, and in the middle of the coronavirus pandemic that has thrown millions out of work, killed more than 100,000 people in the U.S. and disproportionately affected black people.

On Friday, the officer who held his knee to Floyd’s neck was arrested and charged with third-degree murder and second-degree manslaughter — but that appeared to provide little balm. Many protesters are demanding the arrests of the three other officers involved.

Comments from President Donald Trump stoked the anger, when he fired off a series of tweets criticizing Minnesota’s response, ridiculing people who protested outside the White House and warning that if protesters breached the fence, “they would … have been greeted with the most vicious dogs, and most ominous weapons, I have ever seen.”

Leaders in many affected cities have voiced outrage over Floyd’s killing and offered sympathy for those who were protesting — but as unrest intensified, many spoke of the desperate need to protect their cities and said they would call in reinforcements, despite concerns that could lead to more heavy handed tactics.

Minnesota has steadily increased the number of National Guardsmen it says it needs to contain the unrest, and has now called up 1,700. He is also considering a potential offer of military police, which the Pentagon put on alert.

Georgia’s governor declared a state of emergency early Saturday to activate the state National Guard as violence flared in Atlanta. Portland, Oregon, Mayor Ted Wheeler also declared an emergency and ordered a nighttime curfew for the city. The mayor of Cincinnati announced a curfew Saturday and Sunday following damage to about 50 businesses during protests there.

The Guard was also on standby in the District of Columbia, where a crowd grew outside the White House and chanted curses at Trump. Some protesters tried to push through barriers set up by the U.S. Secret Service along Pennsylvania Avenue, and threw bottles and other objects at officers wearing riot gear, who responded with pepper spray.

“I just feel like he’s just one of many names that we’ve had to create hashtags and T-shirts and campaigns for and I feel like nothing has changed,” district resident Abe Neri said of Floyd. “And so that’s why I’m out here. Yeah, when you say nothing you’re taking the side of the oppressor.”

A person was killed in downtown Detroit just before midnight after someone in an SUV fired shots into a crowd of protesters near the Greektown entertainment district, police said. And police in St. Louis were investigating the death of a protester who had climbed between two trailers of a Fed Ex truck and was killed when it drove away.

Atlanta saw some of the most extreme unrest. While crews in that city worked to clean up glass and debris from rioting the night before, a large electronic billboard on Saturday morning still carried the message, “If you love Atlanta PLEASE GO HOME,” echoing the mayor’s pleas.

National Guard members blocked anyone from approaching heavily damaged buildings, including the College Football Hall of Fame and nearby restaurants.

“This is not in the spirit of Martin Luther King Jr.,” Atlanta Mayor Keisha Lance Bottoms said. “You are disgracing the life of George Floyd and every other person who has been killed in this country.”

Bottoms was flanked by King’s daughter, Bernice King, and rappers T.I. and Killer Mike.

“We have to be better than burning down our own homes. Because if we lose Atlanta what have we got?” said Killer Mike, crying as he spoke.

Video posted to social media showed New York City officers using batons and shoving protesters down as they took people into custody and cleared streets. One video showed on officer slam a woman to the ground as he walked past her in the street.

Demonstrators rocked a police van, set it ablaze, scrawled graffiti across its charred body and set it aflame again as officers retreated.

“There will be a full review of what happened tonight,” Mayor Bill de Blasio tweeted, referring to the Brooklyn protest. “We don’t ever want to see another night like this.”

Underscoring that Floyd’s killing is part of a pattern, the names of black people killed by police, including Eric Garner, who died on Staten Island in 2014, were on signs and in chants.

“Our country has a sickness. We have to be out here,” said Brianna Petrisko, among those at lower Manhattan’s Foley Square, where most were wearing masks amid the coronavirus pandemic. “This is the only way we’re going to be heard.”

In Houston and Dallas, Los Angeles and Oakland, California., protesters blocked interstates, but much of the ire in many cities was focused at police. In Portland, Oregon, protesters lit a fire inside police headquarters.

Protesters in Houston, where Floyd grew up, included 19-year-old Jimmy Ohaz from the nearby city of Richmond, Texas: “My question is how many more, how many more? I just want to live in a future where we all live in harmony and we’re not oppressed.”