US president Barack Obama has appealed for calm as enraged protesters set fire to buildings and cars and looted businesses after a grand jury decided not to indict a white police officer over the fatal shooting of unarmed black teenager Michael Brown in Ferguson, Missouri.
Ferguson burned through the night despite pleas for calm from Mr Obama and the family of the victim after prosecutors announced officer Darren Wilson, 28, faces no state criminal charges.
The destruction appeared to be much worse than protests following 18-year-old Mr Brown’s death in August. Authorities used tear gas to try to disperse protesters and reported hearing hundreds of gunshots, which for a time prevented fire crews from fighting the flames.
Authorities later said more than 80 people were arrested as chaos enveloped sections of the St Louis area overnight.
St Louis County police released records showing 61 people were arrested in Ferguson on charges including burglary and trespassing. St Louis Mayor Francis Slay added that 21 people were arrested in the city.
Officer Wilson’s fatal shooting of Mr Brown during an August 9 confrontation ignited a fierce debate over how police treat young African-American men, and focused attention on long-simmering racial tensions in Ferguson and around the US, four decades after the 1960s civil rights movement.
Police were criticised for responding to protests with armoured vehicles and tear gas.
Speaking at the White House, the US president said some Americans might be angry, but need to accept the grand jury’s decision.
Mr Obama added: “We are a nation built on the rule of law, so we need to accept that this decision was the grand jury’s to make.”
He echoed Mr Brown’s parents in calling for any protests to be peaceful.
The vast majority of protesters had left the streets by late on Monday, but looting and gunfire was reported well after midnight.
St Louis County prosecuting attorney Bob McCulloch stressed that the grand jurors, who had met every week since August 20, were “the only people who heard every witness ... and every piece of evidence”.
He said many witnesses presented conflicting statements that were ultimately inconsistent with physical evidence.
As Mr McCulloch read his statement, Michael Brown’s mother, Lesley McSpadden, was sitting on top of a vehicle, listening to a broadcast of the announcement.
When she heard the decision, she burst into tears and began screaming before being whisked away by supporters.
Protesters poured into the streets, overran barricades and taunted police. Some chanted “murderer”, others threw rocks and bottles or smashed police car windows.
Officers eventually lobbed tear gas from inside armoured vehicles to disperse the crowds. There were at least 29 arrests initially, police said.
Thousands of people protested from Los Angeles to New York, leading marches, waving signs and chanting “Hands Up! Don’t Shoot,” the slogan that has become a rallying cry in protests over police killings.
Mr Brown’s family released a statement saying they were “profoundly disappointed” with the decision, but asked people to “channel your frustration in ways that will make a positive change”, adding: “We need to work together to fix the system that allowed this to happen.”
The Federal Aviation Administration lifted flight restrictions in the St Louis area following earlier reports of gunshots being fired into the sky.
About 10 inbound flights were cancelled or diverted late on Monday.