Freddie Gray protests
Baltimore protests over Freddie Gray's unexplained death in police custody turn violent.Getty

The governor of Maryland declared a state of emergency after protesters hurled bricks, looted businesses and set fires in Baltimore on Monday 27 April during violence that followed the funeral of a 25-year-old black man who died after he was injured in police custody.

And Baltimore city mayor Stephanie Rawling-Blake stated that a week-long citywide curfew will start at 10pm and last until 5am.

She described the violent unrest as "very disturbing".

"Too many people have spent generations building up this city for it to be destroyed by thugs who in a very senseless way are trying to destroy what so many folks have fought for," she says.

"We are deploying every resource possible to try to regain control," she said.

Asked why she took so long to get up to speed, she said: "We've been managing the situation. You have to balance the call with actually managing and calling press events."

Baltimore Riots
Demonstrators jump on a damaged Baltimore police department vehicle during clashes in Baltimore, Maryland April 27, 2015. Several Baltimore police officers were injured on Monday in violent clashes with young people after the funeral of a black man, Freddie Gray, who died in police custody, and local law enforcement warned of a threat by gangs.Reuters

She continues: "There's a lot of moving parts and I wanted to make sure I was dedicated to that."

A spokesman for the Baltimore City Police said that 15 officers have been injured in the unrest. He says that two are still being treated in hospital after being hit by "flying debris".

In a statement released on Monday, the governor's office said he was closely monitoring the situation and was in contact with Baltimore Mayor Stephanie Rawlings-Blakes office.

"Today's looting and acts of violence in Baltimore will not be tolerated. In response, I have put the Maryland National Guard on alert so they can be in position to deploy rapidly as needed," Governor Larry Hogan said. "I strongly condemn the actions of the offenders who are engaged in direct attacks against innocent civilians, businesses and law enforcement officers. There is a significant difference between protesting and violence and those committing these acts will be prosecuted under the fullest extent of the law."

The riots broke out just a few blocks from the funeral of Freddie Gray and then spread through parts of Baltimore in the most violent US demonstrations since looting in Ferguson, Missouri, last year.

Hogan put the state's National Guard on alert and additional state troopers were sent to Baltimore. An Orioles baseball game was cancelled and schools, businesses and train stations shut down in the city of 662,000 people 40 miles (64 km) from the nation's capital.

Gray's death on 19 April reignited a public outcry over police treatment of African Americans that flared last year after the killings of unarmed black men in Ferguson, New York City and elsewhere.

A string of deadly confrontations between mostly white police and black men, and the violence it has prompted, will be among the challenges facing U.S. Attorney General Loretta Lynch, who was sworn in on Monday 27 April.

Following her swearing in, Lynch signaled that improving relations between police and the communities they protect will be high on her agenda.

"We can restore trust and faith both in our laws and in those of us who enforce them," she said.

Baltimore police initially showed restraint, but then began arresting people and prepared to use teargas and pepper spray.

"It is disappointing just a few hours after putting Gray to rest," Reverend Jamal Bryant who spoke at the funeral told reporters. "This is not what the family asked for today of all days. This was a day of sacred closure."

Bryant said pastors and other community leaders were going to the scene to try to calm riots and prevent looting.

Hit TV show The Wire was based in Baltimore

Baltimore Police Captain Eric Kowalczyk said at a briefing that one of the injured police officers was unresponsive and several had broken bones.

Earlier, police urged officers to take steps to ensure their safety after they reported receiving a "credible threat" of attacks on law enforcement.

The largely black city has long struggled with high crime and gangs, a reputation that has made it the setting for gritty television police dramas such as "The Wire." Last year officials adopted one of the strictest youth curfews in the United States in an effort to tackle its crime problems.

At the funeral, speaker after speaker before the crowd packing the 2,500-seat New Shiloh Baptist Church said the world was watching to see if justice would be done for Gray.

Before the service, Gray's body, clad in a white shirt, black tie and dark pants, lay in an open white coffin in front of the altar as mourners passed by. The coffin was closed during the service.

Gray was arrested on 12 April 12 he fled from police in a high-crime area. He was carrying a switchblade knife, and he was put inside a transport van to be taken to a police station.

At some point, Gray suffered the spinal injury that led to his death a week later. City Police Commissioner Anthony Batts said on Friday that officers failed to belt him into his seat securely and to give him timely medical attention.

Police have said they would conclude their investigation by Friday and forward the results to state prosecutors. Six officers have been suspended, and the U.S. Justice Department is investigating the incident for possible civil rights violations.