ENRAGED protesters have set fire to buildings and cars and looted businesses in Ferguson, Missouri, after a grand jury decided not to indict a white police officer over the death of an unarmed black 18-year-old, whose shooting exposed deep racial tensions between African-Americans and police.

Ferguson burned through the night despite pleas for calm from President Barack Obama and the family of Michael Brown after St Louis County's top prosecutor announced the officer would face no state criminal charges.

The destruction appeared to be much worse than the protests after Mr Brown's death in August when 61 people were arrested. The authorities used tear gas to try to disperse the latest protesters and reported hearing hundreds of gunshots, which for a time prevented fire crews from fighting the flames.

Officer Darren Wilson's fatal shooting of Mr Brown during a confrontation on August 9 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.

Those protests, which lasted for weeks, were often peaceful, but sometimes violent. Yesterday's protests were "probably much worse than the worst night we ever had in August" after Mr Brown was killed, said St Louis County Police Chief Jon Belmar, who added that police had not yet fired a shot.

He said the fabric of the community had been torn apart in Ferguson, a predominantly black community patrolled by an overwhelmingly white police force.

Mr Belmar said unless his agency could bring in 10,000 officers "I don't think we can prevent folks who really are intent on destroying a community."

Mr Obama said from the White House that some Americans might be angry but needed to accept the grand jury's decision.

He said: "We are a nation built on the rule of law, so we need to accept this decision was the grand jury's to make."

He echoed Mr Brown's parents in calling for any protests to be peaceful.

St Louis County Prosecuting Attorney Bob McCulloch stressed the grand jurors, who had met weekly since August 20, were "the only people who heard every witness ... and every piece of evidence." He said many witnesses presented conflicting statements which were ultimately inconsistent with physical evidence.

When Mr Brown's mother Lesley McSpadden 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 shattered the windows of police cars.

Thousands 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.

The Federal Aviation Administration diverted at least 10 St Louis-bound flights because of reports of gunshots fired into the sky.

Mr Brown's family released a statement saying they were "profoundly disappointed" at the decision.