United States: A grand jury has brought charges against six Baltimore police officers in the death of a black man who suffered fatal neck injuries while in police custody, a case that touched off angry protests and a day of looting and arson in the Maryland city.

The charges, including a count of second-degree murder against one of the officers involved in the arrest of Freddie Gray, were announced on Thursday by Baltimore City State's Attorney Marilyn Mosby.

The officers, three white men and three African Americans including a woman, will formally hear the charges and enter pleas at a 2 July arraignment.

Mosby, a 35-year-old African American who took office in January, surprised many Baltimoreans early this month by announcing her swift decision to seek the charges.

Under the US judicial system, grand juries are empowered to hear a prosecutor's evidence and return charges against a defendant if the panel agrees there is probable cause to do so.

‘These past two weeks, my team has been presenting evidence to a grand jury that just today returned indictments against all six officers,’ Mosby told reporters. She took no questions.

Gray, 25, died on 19 April, a week after he was arrested and driven in a police van to a station house for booking. On the way, the vehicle stopped four times, the prosecutor has said, and Gray sustained injuries sometime during the ride. Mosby said officers repeatedly ignored Gray's pleas for medical attention.

His death set off weeks of largely peaceful protests in Baltimore punctuated by a day of unrest after his funeral on 27 April, when rioters threw rocks at police and set buildings and cars on fire.

It followed a string of police-involved killings of unarmed black men, notably in Ferguson, Missouri, New York City and North Charleston, South Carolina.

The cases have fueled waves of protests across the United States over what civil rights activists say is law enforcement's unjustified use of lethal force against minority groups.

In Baltimore, the grand jury charged Officer Caesar Goodson Jr., the driver of the police van, with second-degree ‘depraved heart’ murder, manslaughter and reckless endangerment.

Lieutenant Brian Rice, Sergeant Alicia White and Officer William Porter were charged with manslaughter, assault and reckless endangerment.

Officer Edward Nero and Officer Garret Miller both face assault and reckless endangerment charges.

The grand jury decided against bringing charges of false imprisonment against Rice and Nero. Mosby initially said she would pursue those charges against the two arresting officers.

The Fraternal Order of Police union, which represents the officers, did not immediately respond to a request for comment.

The US Bureau of Alcohol, Tobacco, Firearms and Explosives released photos on Thursday of several people suspected of setting fires during the 27 April rioting. They included a man suspected of torching a CVS pharmacy, where arson and looting became a symbol of the unrest. Authorities are offering $10,000 rewards in the cases.

The ATF has investigated the torching of six stores and a seniors' center under construction, it said in a statement. The Baltimore Fire Department has said 61 structural fires were recorded over 27 and 28 April. In addition, 144 vehicles were set on fire, Mayor Stephanie Rawlings-Blake's office has said.

In a Reuters/Ipsos poll taken after the protests in Baltimore, 69 percent of respondents said America had a serious issue with race. Nearly three-quarters said there was more racism in the United States than the country was willing to admit.