Thousands of protesters hit the streets of Baltimore again despite the charging of six police officers over the death of a 25-year-old African American whose spine was snapped in custody.

The charges -- ranging from second-degree murder and manslaughter to misconduct -- were set out in a surprise announcement by Maryland state prosecutor Marilyn Mosby.

All six officers -- three of them black and three white, according to mugshots broadcast by CNN -- were taken into custody and later posted bond, reports said.

The death of Freddie Gray, 25, just the latest black American to lose his life at the hands of police, has reignited simmering resentment in the United States over police tactics, particularly in their dealings with African Americans.

"The findings of our comprehensive, thorough and independent investigation, coupled with the medical examiner's determination that Mr. Gray's death was a homicide... have led us to believe that we have probable cause to file criminal charges," Mosby said.

Mosby said Gray "suffered a severe and critical neck injury as a result of being handcuffed, shackled by his feet and unrestrained" inside a moving police van following his arrest on April 12.

En route to a police station, the police van stopped at least three times, including once to pick up a suspect in an unrelated case.

Cheers broke out when Mosby unveiled the charges on the steps of Baltimore's war memorial, across the street from city hall, a focal point of protests demanding justice and change.

Baltimore's police union condemned what it called "an egregious rush to judgement" as it defended the officers and expressed confidence they would be vindicated.

"We believe that these officers will be vindicated as they have done nothing wrong," said Michael Davey, a lawyer for the city's Fraternal Order of Police, suggesting that prosecutors had succumbed to pressure from days of demonstrations.

Many in Baltimore, an East Coast port city of 620,000 about an hour's drive north of Washington, had expected Mosby to say that the case was still under investigation.

- More protests -

But if nervous authorities had hoped the announcement would ease palpable tensions on the streets, a march that grew bigger by every passing hour suggested otherwise.

Several thousand people rallied from City Hall through downtown streets lined with riot police, demanding justice and an end to alleged racism and police brutality.

As they walked past a phalanx of officers, many chanted: "Send those killer cops to jail, the whole damned system is guilty as hell."

Some held aloft placards thanking Mosby, but others cautioned that the charges were only a first step.

Brian Carter, a nurse, 39, told AFP: "I was overwhelmed with joy, I'm not going to lie. The Baltimore police, they're not all bad, but they are very prejudiced towards people."

With an emergency curfew again swinging into effect at 10:00 pm (0200 GMT Saturday) in the city, Carter, added: "I think that people are going to be compliant with the law because they finally got what they wanted."

Smaller demonstrations have also broken out in recent days in New York, Philadelphia, Washington and Boston, and hundreds again congregated in Union Square, in the center of Manhattan, as police helicopters buzzed overhead.

"It's not just Baltimore, it's everywhere in this country. I think people are realizing what's going on," said "AJ," a 21-year-old student from New Jersey.

- 'Shock' -

William Murphy, a lawyer for the Gray family, told reporters they had no advance word of the charges.

"We were in shock -- and it was a good shock, do you know what I mean?" he said, while Gray's step-father Richard Shipley appealed for peace to prevail in the city.

Gray, who had a record of non-violent drug offenses, died a week after his arrest from spinal injuries sustained when he was arrested in a west Baltimore public housing project.

Facing the most serious charge, one of second-degree murder, is an African American, Caesar Goodson, the driver of the van that transported Gray to a police station.

Goodson, 45, was also charged with involuntary manslaughter, second-degree assault, vehicular manslaughter and misconduct.

Goodson got out of the van to check on Gray's condition, Mosby said, but "at no point did he seek nor did he render any medical assistance."

Three other officers were charged with involuntary manslaughter, second-degree assault and misconduct, and two more charged with second-degree assault and misconduct.

One officer was also charged with false imprisonment.

Mosby -- an African-American woman who is the daughter, granddaughter and niece of police officers -- said Gray had been "illegally arrested" as "no crime had been committed."

In an open letter, Baltimore's police union called for a "special independent prosecutor" to take over the case from Mosby, who at 34 is America's youngest big-city chief prosecutor.

- Conflicts of interest? -

It cited Mosby's relationships with Murphy, who contributed $5,000 to her election campaign, and her husband, a city council member who represents the poverty-stricken section of Baltimore where Gray lived and died.

Baltimore police lieutenant Kenneth Butler added: "We are extremely frustrated and shocked by the circumstances that have transpired today."

Gray has become the latest face of an intense national debate over whether American police are too quick to use violence against unarmed black males.

In the best-known case, a white police officer fatally shot unarmed teenager Michael Brown in Ferguson, Missouri -- prompting riots in the St. Louis suburb -- but was not indicted by a grand jury.

At the White House, President Barack Obama said it was "absolutely vital" for the truth in Baltimore to come out.
Source: AFP