BALTIMORE » At a grassy plaza across from Baltimore’s City Hall filled with thousands of people on Saturday, speakers praised the city’s young top prosecutor for quickly moving forward with charges against the police officers they see as responsible for the death of a 25-year-old black man who suffered a fatal spinal injury in their custody.

The peaceful scene was a striking contrast to demonstrations the past two weeks at the same plaza. Crowds of angry protesters demanded that the city’s leaders heed their cries for justice, and one night, the protests gave way to looting, rioting and arson.

On Friday morning, four days after the most violent civil unrest since the assassination of the Rev. Martin Luther King in 1968, State’s Attorney Marilyn Mosby had stood nearby before a bank of television cameras beaming her words live around the world. She announced criminal charges against the officers ranging from assault to murder in the death of Freddie Gray, whose name has become a rallying point against police brutality and socio-economic inequality in American cities.

"To the youth of the city," Mosby, 35, said as she announced the charges. "This is a moment. This is your moment. … You’re at the forefront of this cause and as young people, our time is now."

Organizers billed the big Saturday afternoon demonstration not as a protest of Gray’s death, but a "victory rally" that city leaders have perhaps listened to their cries. Smaller groups of what looked to be several hundred gathered all around the city and made their way through the streets to join the thousands at the main rally.

Chants of "no justice, no peace, no racist police" echoed and crowds of people, black and white, young and old, carried homemade signs calling for peace, as well as printed ones asking for justice. Others wore T-shirts that read, "Black Lives Matter," a slogan many have taken up in the fight.

The Gray case is the latest in a string of high-profile killings of black men by police that include Michael Brown in Ferguson, Missouri, and Eric Garner in New York City, neither of which resulted in charges against the lawmen.

Unlike Brown and Garner, Gray’s death happened in a majority black city where black elected officials hold the reins of political power and oversee the justice system. The police department is 48 percent black. Even the officers charged are racially split — three white, three black.

"I think it has to do with Ms. Mosby living here in West Baltimore: they took seriously the sentiment of the youth," said Kustanya McCray, a 41-year-old Baltimore resident who joined thousands of people at the demonstration. "Our city council, the mayor_they’re all from here. They’ve lost family members to violence. They understand what’s been happening. They understand they have no choice now."

After the night of rioting and looting, the National Guard was called in to help police enforce a nightly curfew with heavily armed troops riding in armored vehicles, to which many objected.

As of 11 p.m. on Saturday, a handful of people had been arrested, including one that was hit with a blast of pepper spray and later taken away in an ambulance.

Mosby said in charging the officers that police had no reason to stop or chase after Gray. They falsely accused him of having an illegal switchblade when it was a legal pocketknife. The van driver and the other officers failed to strap him down with a seat belt, a direct violation of department policy, and they ignored Gray’s repeated pleas for medical attention, even rerouting the van to pick up another passenger, she said.

Mosby said Gray’s neck was broken because he was handcuffed, shackled and placed head-first into a police van, where he was left to slam against the walls of the small metal compartment. She deemed the death a homicide.

The Gray case has brought to the forefront problems that have festered in Baltimore for more than a half-century: poverty, crumbling infrastructure, joblessness, racial tension, and neighborhoods plagued by neglect, drugs, violence and a heavy police presence, and prompted repeated refrains of "Black Lives Matter."

The reverberations through the streets of Baltimore have extended far past its borders.

Protests have swept across Philadelphia, Austin, Dallas, Boston and New York in response to Gray’s death and the cities’ own tense relationships with their police forces.

In Baltimore, before the racially and economically diverse crowd in City Hall plaza, Black Lawyers for Justice president Malik Shabazz praised Mosby for her decision, and called on the citizens of Baltimore to protect her.

"Every prosecutor should have such backbone," he said. "Every prosecutor should have such spine.

"We’ve always got the cuffs on us," he continued, "now the real criminals have the cuffs on them. Make sure no harm comes to this black woman who is prosecuting these police officers, because if any harm comes to this prosecutor while she is prosecuting this case we will hold Baltimore and America thoroughly accountable."

As Shabazz’s amplified criticisms of the police echoed off nearby buildings, heavily armed officers and national guardsmen stood cross-armed near armored vehicles barricading the streets surrounding the plaza and peering at protesters through binoculars from their perch on a nearby rooftop. A police helicopter circled high above.

Earlier in the day, demonstrators gathered in Sandtown, the poor, predominantly black West Baltimore neighborhood where Gray was raised and arrested. Among the throng was Kweisi Mfume, the former congressman and president of the NAACP, who said the charges are a response to the passion and fury of young Baltimore residents.

"This current generation has realized that it has to shape its destiny and not wait for it to be shaped," Mfume said. "I think now they’re starting to come to grips with the enormity of this and what they have caused to take place nationwide, and are embracing the fact that perhaps, this is our civil rights movement."

Associated Press writers Jessica Gresko and Amanda Lee Myers contributed to this report.