Fires continued to burn in the mainly black northeastern city, where a curfew was set to take effect Tuesday evening after a day of riots that dragged on into Monday night.
The state of Maryland declared a state of emergency after rioters ransacked shops, making off with armloads of merchandise.
Schools were closed Tuesday a safety measure.
The full extent of the damage wrought in the latest American city, where simmering tensions over police treatment of young blacks have exploded, was likely to become clearer during the day.
City officials, black community leaders and the family of 25-year-old Freddie Gray expressed disgust over the degeneration of the protests following his funeral.
"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 tear down what so many have fought for," Mayor Stephanie Rawlings-Blake said.
"It's idiotic to think that by destroying your city, you're going to make life better for anybody," she said.
TV footage showed one mother slapping her son repeatedly in the head and screaming at him for taking part in the unrest.
Thousands of police and National Guard troopers were deployed to back up beleaguered officers as the riots spread on Monday evening.
At least 27 people were arrested and 15 police injured in clashes with stone-throwing mobs -- many of them high school students -- who also attacked local businesses.
The Baltimore Sun newspaper, quoting police, reported two people injured in separate shootings. The police were not immediately available to confirm this.
The violence is the latest in a series of confrontations between US police and mainly young African American 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 was sparked by the case of Freddie Gray, who died on April 19 of spinal injuries apparently suffered during his arrest earlier this month.
Despite appeals for calm from his family, roving gangs of youths fought pitched battles with police. Several news reporters were assaulted and had equipment stolen.
Police said they were combing through video footage to identify other possible offenders aside from those already arrested.
National Guard deployed
While most of the violence was in the west of the city, a large building on Baltimore's east side was also torched.
Maryland police superintendent Colonel William Pallozzi said he had ordered 500 police into the city and requested 5,000 more from the wider 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.
President Barack Obama was briefed on the rapidly evolving situation by Rawlings-Blake and his new Attorney General Loretta Lynch, the White House said.
The Baltimore Orioles baseball team cancelled its evening game.
The rioting erupted shortly after thousands of mourners gathered for Gray's funeral in New Shiloh Baptist church in the city's impoverished Sandtown neighborhood.
Before the service, a cryptic message circulated on social media called for an after-school "purge," street slang for random acts of lawlessness.
'Absolutely inexcusable'
Gray's grieving family had explicitly asked for no protests.
"Today of all days, the family was clear this was a day of sacred closure," said pastor Jamal Bryant, who delivered the eulogy.
At the funeral, Gray's white casket, which was surrounded by wreaths, lay next to a Los Angeles Dodgers baseball cap and a sign reading "Peace y'all."
Crowds swayed to hymns and chanted "justice shall prevail, peace will prevail."
Violence had also erupted on Saturday when 34 people were arrested and six police officers were injured after an orderly rally for Gray outside Baltimore city hall.
Police on Monday announced they had received a "credible threat" that criminal gangs in Baltimore had "entered into a partnership to 'take out' law enforcement officers."
Lawyers for Gray's family say his death, after a week in a coma, was caused by severe spinal injuries sustained following his arrest.
Six officers have been suspended with pay pending the outcome of a police investigation that is to be submitted to state prosecutors by Friday.
Police confirmed Gray had requested medical help and an inhaler after he was detained and have acknowledged he should have received medical attention sooner.
In video taken by bystanders, Grey can be heard howling in pain as his limp body is dragged into the van during his arrest.
source: interaksyon.com
