There has been rioting and looting in the US town of Ferguson, Missouri after a jury decided not to bring charges over the killing of a black teenager.
Michael Brown was shot by a white police officer, Darren Wilson, on August 9, sparking protests.
A police chief said the latest violence in the suburb of St Louis, Missouri, was “probably much worse” than on any night since the teenager’s death.
St Louis County police chief Jon Belmar said rioters had fired 150 shots.
Many in the African-American community had called for Mr Wilson to be charged with murder, but after three months of deliberation a Missouri grand jury – of nine white and three black members – made no recommendation of charges.
President Barack Obama joined the teenager’s family on Monday in appealing for calm, urging Americans to accept the decision was “the grand jury’s to make”.
Demonstrators flooded on to the streets of Ferguson after the verdict, with several buildings set alight.
Police were heavily armed but say they did not use their firearms during the rioting overnight.
Several cars were set on fire during protests in Dellwood, an area of St Louis close to Ferguson. Many residents and business owners took to the streets early on Tuesday to begin the clean-up.
Authorities said more than 80 people were arrested amid chaos in several areas of St Louis overnight. Sixty-one of those arrests were in Ferguson, with charges including burglary and trespassing.
As protesters charged barricades, hurling glass bottles, police responded with smoke and tear gas.
Thousands of people also protested in 90 other US cities, from Los Angeles to New York. In Oakland, California, they blocked traffic on a major highway in the San Francisco Bay area.
Much of the debate since August has centred on whether Michael Brown was attempting to surrender to Darren Wilson when he was shot, and protesters have adopted the chant “Hands up, don’t shoot”.
But state prosecutor Robert McCulloch, speaking after the grand jury decision, said physical evidence had contradicted some of the witness statements.
Brown family ‘profoundly disappointed’
Mr Brown’s family said in a statement: “We are profoundly disappointed that the killer of our child will not face the consequence of his actions.”
But they also appealed for calm, saying: “Let’s not just make noise, let’s make a difference”, and calling for all police to wear body cameras.
Mr Brown’s mother, Lesley McSpadden, wept at news of the jury’s decision as she was comforted by supporters outside the police station in Ferguson.
Mr Brown’s family could yet file a wrongful-death lawsuit against Mr Wilson.
Meanwhile, a justice ministry investigation is still under way into whether the police officer violated Mr Brown’s civil rights.
Darren Wilson, 28, is currently on paid leave and has kept out of the public eye.
The ministry is also investigating practices at the Ferguson police department.