Heaping violent contempt on an 8 p.m. curfew declaration and on widespread pleas for forbearance and peace, rioters rampaged across Minneapolis for a fourth night Friday and into early Saturday, creating unprecedented havoc as they set towering fires, looted and vandalized businesses and shot at police officers, all in response to the death of an unarmed black man under a white police officer's knee on Monday.

By early Saturday, Gov. Tim Walz and other leaders had weighed in to say that the worst violence may have been perpetrated by outsiders with various agendas, not by the thousands of mostly peaceful protesters who joined marches and rallies during the day.

By all accounts, a law enforcement presence was almost undetectable as the violence rapidly accelerated until just before midnight and into early Saturday, when hundreds of police officers, state troopers and National Guard troops, some in armored vehicles, fanned out into troubled areas, confronting rioters with mass force, tear gas and orders to disperse issued via bullhorn.

And yet, those efforts had visibly little impact for much of the night, and questions swirled among citizens and politicians about how such a dire situation could have developed in a long peaceable, progressive city.

The fresh violence came despite Friday's charges against Derek Chauvin, the police officer suspected in the death of George Floyd, the unarmed black man who died after being detained on suspicion of passing a counterfeit bill.

At 1:30 a.m. Saturday, a visibly exhausted Walz and Minneapolis Mayor Jacob Frey held a lengthy, emotionally ragged news conference. Walz began by saying that he had talked to Floyd's family and that they agreed what was happening in Minneapolis was horrific and counterproductive.

"The absolute chaos — this is not grieving, and this is not making a statement [about an injustice] that we fully acknowledge needs to be fixed — this is dangerous," Walz said. "You need to go home."

Implying that organized outsiders, perhaps including anarchists, white supremacists and drug cartel agents from outside Minnesota, were contributing to the chaos, Walz said, "The sheer number of rioters has made it impossible to make coherent arrests. ... The capacity to be able to do offensive action was greatly diminished" by the sheer scope and seemingly carefully organized nature of the assaults.

"The terrifying thing is that this resembles more a military operation now as you observe ringleaders moving from place to place," he said.

"I will take responsibility for underestimating the wanton destruction and the sheer size of this crowd," Walz said. He said repeatedly that the sheer scope of the crowds and violence have been shocking, and that there was no way for authorities to anticipate or prepare for such an onslaught.

"There are simply more of them than us," he said.

Comparing this week's events to the actions he has undertaken in relation to the COVID-19 epidemic, Walz said, "A compact that we go by in civilized society is that you have to have social buy-in," which rioters do not acknowledge, he said. He said law enforcement has had to focus on protecting large institutions such as the Federal Reserve and power plants, acknowledging that that emphasis has come at the expense of small businesses, many of them family- and minority-owned, that have gone up on flames or been plundered by looters.

An emotional Frey added, "Minneapolis, I know you are reeling. ... We as a city are so much more than this. We as a city can be so much better."

Once again, Frey made an impassioned plea for an end to the violence, saying that it was only hurting residents, not "getting back" at the police. "If you have a friend or a family member that is out there right now, call them and tell them to come home," he pleaded as rioting raged nearby. "It is not safe. It is not right."

John Harrington, commissioner of the state Department of Public Safety, also spoke at the wee-hours news conference, saying that efforts would continue overnight to push rioters back from downtown and business areas, but "we will need far more officers and far more National Guard officers than we have."

The violence occurred after many businesses and public structures had been boarded up and fortified in preparation for yet another night of violent demonstrations against police brutality.

After midnight, as helicopters drummed above Minneapolis and smoke blanketed the shellshocked city, major fires were reported near the Minneapolis Police Department's Fifth Precinct headquarters at Nicollet Avenue and 31st Street, including at the U.S. Post Office on Nicollet, a Wells Fargo Bank, a Stop-and-Go gas station and a Shell station on Park Avenue and Lake Street. Amid fears that accelerants at the gas stations could explode, onlookers scattered and ducked. Fire officials said they could not get to many sites without security, but later were able to make their way to most of them.

Authorities also reported that shots had been fired at officers in the Fifth Precinct area, but there were no reports of injuries.

Police also fired into a car that barreled into a group of officers in downtown Minneapolis late Friday, but no one was hit.

The continued destruction raised major questions about the presence and strategy of law enforcement and the National Guard, which Walz initially called in Thursday to help keep the peace.

Early Saturday, Sen. Paul Gazelka, the state Senate's majority leader, lambasted Walz anew for what he called a lack of leadership. He was among many GOP political leaders, including President Donald Trump, who have weighed in to decry the situation and the leadership of Walz and Frey.

Gazelka told a Star Tribune reporter that he called the White House about the Minnesota riots, although he was not able to speak directly with Trump. "I said, 'Minnesota needs you,'" Gazelka said. "'Our governor is not able to keep the peace. And we need help before our city burns down.'"

Gazelka said he did not know if his call was what prompted the Pentagon to announce early Saturday that it had put the military on alert in case it was needed in Minneapolis.

"This is a failure of leadership at the governor's level," Gazelka said. "He is the commander-in-chief. He controls the National Guard. He needs to lead."

He said Walz should have called out 2,000 National Guard troops, not just 500.

At early Saturday's news conference, Walz said that the state is seriously considering accepting the type of military help proffered by the Pentagon, especially if it includes national intelligence assistance about outside forces contributing to the violence in Minneapolis.

"Why are we talking about anarchists who are burning down damn buildings that were built up by indigenous owners" instead of talking about a police officer whose actions led to the death of a citizen?, he said, describing the escalation in the scope of the violence since Monday. The genesis of the outrage and protests has been lost in the riot leaders' manipulative chaos, he claimed.

About an hour before the news conference, Walz tweeted that law enforcement was being deployed en masse to trouble spots. The Minnesota Police and Peace Officers Association quickly replied that its members did not have nearly the amount of resources needed to address the severity of the crisis, and called for more leadership on his part.

At Minneapolis' Third Precinct police headquarters, which was torched early Friday, State Patrol troopers fired tear gas at protesters just before the curfew took effect, but later, cars burned not far away and there appeared to be no presence of law enforcement or firefighters.

Downtown, a few officers on bicycles didn't interfere with a roaming protest, which grew after the 8 p.m. curfew and passed the First Precinct police station without stopping before it made its way onto Interstate 35W. According to MnDOT traffic cameras, protesters later set a bonfire in the southbound lanes just south of Washington Avenue.

At the Fifth Precinct in south Minneapolis, 350 officers moved into the area just before midnight, pushing back demonstrators. Several officers stood on top of the building watching the mostly peaceful crowd, which was chanting and holding signs. Meanwhile, a nearby Sprint Store, Office Max and convenience store were looted. Near midnight, police officers and National Guard troops were moving into the area.

Early Saturday, fires were also burning at businesses on W. Broadway. Smoke filled the North Side as firefighters extinguished a blaze at what was once a barbershop at the intersection of N. 26th Avenue. Onlookers watched calmly as police officers also stood by. The scene was peaceful, and at nearby Fourth Precinct headquarters, the site of many demonstrations in months past, things were peaceful.

Bryan Tyner, the Minneapois Fire Department's assistant chief of operations, said late Friday that firefighters were responding to fires throughout the city but "we are not able to respond to sites until the scene can be secured." By early Saturday, firefighters were present at many of the raging fires, surrounded by Guard troops and police officers even as demonstrators hovered nearby.

According to emergency dispatch audio, shots were fired shortly after 8 p.m. at a group of law enforcement personnel on Hiawatha Avenue before two men in white shirts ran away on E. 32nd Street. It was unclear what authority reported the shots fired. They immediately began to retreat.

"Hey guys, east of us is starting to go," a man said referring to a fire in the area. "We don't have a lot of [expletive] out here. Let's keep going. Grab you guys' stuff, grab you guys' people. Let's get out of here."

"Let's get the [expletive] out of here. … If you don't have a car, get in one. Let's go. Right now."

Some leaders had hoped for a reprieve from unruly demonstrations after authorities announced around midday that fired Minneapolis police officer Derek Chauvin had been arrested and was charged with third-degree murder and second-degree manslaughter. Video taken Monday night showed Chauvin kneeling on Floyd's neck for more than 8½ minutes, while Floyd fell unresponsive and was later pronounced dead.

Near the burned Third Precinct police building, many in a crowd of hundreds took a knee with their fists in the air. Some in the crowd said they wouldn't abide by the curfew unless all four officers at the scene of Floyd's death were arrested and charged.

"They can't arrest us all,"some protesters said. But when the tear gas was launched, many fled the area.

Cousins Thomas Mante and DeWayne Counce, who are black, stood on the corner of Lake Street and S. 22nd Avenue on Friday evening as several demonstrators stood in front of a line of National Guardsmen and vehicles parked across Lake Street. "It's a humanity thing," Counce said. "People are fed up," Mante said.

The two said they're glad Chauvin was arrested and charged but said the third-degree murder count was too low. "They're basically saying it wasn't intentional," Counce said. They want to see the other three former officers charged with murder, too.

As he urged peaceful protest earlier in the day, Gov. Tim Walz acknowledged Minnesota's deep-rooted inequity and called for new measures to ensure change this time, after little changed so many times before.

"I'm asking you to help us, help us use a humane way to get the streets to a place where we can restore justice, so that those that are expressing rage and anger and demanding justice are heard," he said. "Not those who throw firebombs into businesses."

'It's not doing any good'

In north Minneapolis, James Clark was among the dozens who stood by as firefighters extinguished what was left of the Fade Factory, a small barbershop on W. Broadway that was fully engulfed. He is the father of Jamar Clark, the black man shot and killed during an encounter with police in 2015, whose death sparked weeks of protest and encampments outside the Fourth Precinct.

"It's not solving anything, it's not doing any good. It's just putting all these different communities in a bad position. They can't get food or prescription jobs," he said. "It don't make no sense."

He urged protesters to send their message in a different way, but he understands the anger, and things will continue.

"This has been building up for over 400 years and it just got to the point where it exploded," he said.

Staff writers Pam Louwagie, Liz Sawyer, Libor Jany, Chao Xiong and Abby Simons contributed to this report.