Baltimore riots: Troops deployed as cleanup begins
Thousands of troops and outside police officers have been deployed to the US city of Baltimore, following violent protests linked to the death of a black man fatally injured in police custody.
A week-long curfew has been announced. Schools and many businesses are closed.
On Monday, hundreds of people set fires, looted stores and confronted police across the city.
City officials have been criticised for not responding more aggressively.
US President Barack Obama said on Tuesday that the riots have unfairly overshadowed the peaceful protests about police use of force.
"There is no excuse for the kind of violence we saw yesterday," Mr. Obama said. "They are not protesters. They are not making a statement. They are stealing."
Volunteers and city workers began cleaning up affected areas on Tuesday morning. Smoke still rose from buildings set alight the night before.
Officials said about 200 people were arrested and more than 100 cars were set on fire on Monday. Fifteen buildings were destroyed.
African-American Freddie Gray, 25, died on 19 April after suffering injuries to his spinal cord and spending a week in a coma. The US justice department is investigating exactly where and when his spinal injuries were sustained.
Officials have suspended six police officers who were involved in the case.
Monday's clashes began hours after Mr Gray's funeral.
Baltimore Mayor Stephanie Rawlings-Blake said it was very clear there was a difference between the "peaceful protests of those who seek justice" and the "thugs who want to incite violence".
National Guard commander Linda Singh said that up to 5,000 troops could be put on the streets.
"We will be out in massive force," she said, adding that armoured vehicles would be used, but the city would not be under martial law.
Extra police officers are also being drafted in from the Mid-Atlantic region.
Earlier, President Barack Obama said his administration would provide whatever assistance was needed.
On the scene: Tara McKelvey, BBC News
Some looted and ransacked the city. Others waited for the chaos to subside - then started to rebuild.
Joseph Adeola stayed even after his store, Best Care Pharmacy, was robbed. He has invested in the neighbourhood and in the country, too. His family is from Nigeria, and he has tried to make a new life here.
Then the riots started. Looters and rioters ransacked sections of the city. Fifteen police officers were injured, and a state of emergency was declared.
National Guard officers are watching over some of the streets. They stand in a line near the harbour, chatting amongst themselves in the bright morning light.
Maryland Governor Larry Hogan issued an executive order to "protect the lives and property of citizens being impacted by this public emergency".
He said calling in the National Guard was a "last resort" and that he had "not made this decision lightly".
Capt Eric Kowalczyk of Baltimore Police said the 15 officers were wounded by thrown objects including bricks and bottles. Two remain in hospital.
Police made at least 27 arrests on Monday.
A fire broke out at a newly constructed community building near a church in the east of the city.
Kevin Harris, a spokesman for the mayor, said the fire was at the Mary Harvin Transformation Centre, described online as a community-based organisation that supports young people and families.
Freddie Gray's death is the latest in a string of high-profile cases where black men have died after contact with the police.
Nationwide protests followed the killing of unarmed black teenager Michael Brown by a white police officer in Ferguson, Missouri, last year.
The violence is an escalation of earlier protests. There were 34 arrests as peaceful demonstrations by about 1,200 people outside Baltimore's City Hall on Saturday afternoon got out of control.