Updated 8.30pm

THOUSANDS OF POLICE and National Guard troopers were ordered to back up beleaguered officers in Baltimore last night after riots triggered by anger over the death of a black man in police custody.

At least 27 people were arrested and 15 police injured as stone and brick-throwing mobs, many of them high school students, clashed with law enforcement and attacked local businesses.

State of emergency

The state of Maryland declared a state of emergency today.

Baltimore Police said this afternoon that a woman was reported to have been shot in the leg earlier today.

This evening, a large crowd has gathered at one part of the city:

Speaking in Washington, President Barack Obama condemned the rioting, but also said that a series of recent incidents — beginning last year with the police shooting of an unarmed teenager in Ferguson, Missouri — was worrying.

Since Ferguson… we have seen too many instances of what appears to be police officers interacting with individuals — primarily African American, often poor — in ways that raise troubling questions.

Obama expressed sympathy for civil rights leaders and protesters — as well as for police on the front line of demonstrations — and said America needed to address the strained ties between officers and blacks.

He said it was important that “we don’t just pay attention to these communities when a CVS burns. And we don’t just pay attention when a young man gets shot or has his spine snapped”.

I think there are police departments that have to do some soul searching

I think there’s some communities that have to do some soul searching. I think we as a country have to do some soul searching. This is not new. It’s been going on for decades.

The violence is the latest in a series of confrontations between US police and mainly young African American young men enraged by what they see as racism in the force.

Last summer’s fatal shooting of unarmed teenager Michael Brown by a white police officer in Ferguson, Missouri triggered coast-to-coast protests.

The unrest in Baltimore started after the funeral of a black man who died April 19 of spinal injuries apparently suffered during his arrest this month.

These are the worst riots in almost half a century, the Financial Times reports.

Despite appeals for calm from 25-year-old Freddie Gray’s family, roving gangs of youths fought street battles with police that left 15 officers hurt, six of them seriously.

AP / Press Association Images AP / Press Association Images / Press Association Images

“Today of all days, the family was clear this was a day of sacred closure,” said pastor Jamal Bryant of the city’s Empowerment Temple church, who delivered the eulogy at Gray’s funeral.

Several news reporters were assaulted and had equipment stolen.

“I think for the vast majority the city is calming itself down slowly but surely, other than the car fires and the street fires,” police chief Anthony Batts told a news conference shortly before midnight, urging parents to “take control of your kids.”

Faith-based leaders are being asked to meet tomorrow night to discuss the issue.

While most of the violence was in the west of the city, as night fell, a large building was also ablaze on Baltimore’s east side.

Maryland police superintendent Colonel William Pallozzi said he had ordered 500 police to the city and requested 5,000 more from the broader Mid-Atlantic region.

And National Guard commander Adjutant General Linda Singh said she had 5,000 troopers ready and would deploy them in “massive force” to protect people and property.

AP / Press Association Images AP / Press Association Images / Press Association Images

“Too many people have spent generations building up this city for it to be destroyed by thugs,” said Rawlings-Blake, who has faced criticism that the city had been slow to act.

President Barack Obama was briefed on the rapidly evolving situation by Rawlings-Blake and his newly sworn in Attorney General Loretta Lynch, the White House said.

Earlier, police had issued a statement warning of reports that rival armed gangs had agreed a truce in order to better target officers.

The Baltimore Police Department / Criminal Intelligence unit has received credible information that members of various gangs including the the Black Guerilla Family, Bloods and Crips have entered into a partnership to ‘take-out’ law enforcement officers. This is a credible threat. Law enforcement agencies should take appropriate precautions to ensure the safety of their officers.

The death of Freddie Gray comes two years after the death of Trayvon Martin, which sparked off the #BlackLivesMatter movement. His death was followed by the shooting of Michael Brown, and the death of Eric Garner.

Freddie Gray, who is black, was arrested after he made eye contact with officers and ran away, police said.

http: / /baltimore.cbslocal.com/CBS Baltimore http: / /baltimore.cbslocal.com/CBS Baltimore / /baltimore.cbslocal.com/CBS Baltimore

He was held, handcuffed and loaded into a van, and leg cuffs were put on him. He asked for medical help several times, said Associated Press.

Paramedics were called after the 30-minute ride in the van. The officers involved in the arrest of Gray are suspended with pay and under criminal investigation by their own department, AP reports.

- © AFP, 2015 Additional reporting Aoife Barry. Originally published 27 April ta 10.40pm.

Read: Baltimore protests: ‘It can’t be business as usual with that man’s spine broken, with no justice’>