Thousands of people have held vigils across the US in honour of a black teenager killed by police in Missouri.

Moments of silence and protests were held in New York, Chicago, Atlanta and elsewhere, five days after Michael Brown, 18, was fatally shot.

After four nights of violence in Ferguson, Missouri, where he died, state police took charge of security.

In contrast on Thursday evening, state troopers and local police walked with protestors, shaking their hands.

Captain Ronald Johnson of the Missouri Highway Patrol, an African-American who grew up nearby, was named as the new head of the operation.

As he walked at the front of a march through the streets, he was seen hugging people he met. "We all want justice. We all want answers," he said.

For the first time, the reverberations from this Midwest town were felt nationwide with dozens of vigils organised by a social media campaign.

The event in Washington DC was attended by hundreds of people in Malcolm X Park, many holding placards saying: "Hands up. Don't shoot".

Similar vigils were held in New York, Boston, Detroit, Chicago and many other cities.

They came at the end of a day when Missouri Governor Jay Nixon had likened the scenes of violence in Ferguson to a "war zone" and the police conduct was questioned.

US Attorney General Eric Holder said the use of military equipment and vehicles in Ferguson had sent a "conflicting message", while President Barack Obama said there was no excuse for police using "excessive force".

The governor then announced that the state highway patrol would direct the security operation. "We're going to have to regain trust," he said.

Hours later, reporter Wesley Lowery of the Washington Post summed up the change in atmosphere on the streets of Ferguson.

"At this time at night on Monday, residents were in real fear for their lives," he said. "Tonight they're taking selfies with cops."

The tension in Ferguson was sparked by the death of Brown, 18, on Saturday afternoon.

Details about the incident have been disputed but eyewitnesses said the unarmed teenager had his arms raised when he was shot multiple times by a police officer.

Police say there was a struggle and the officer suffered facial injuries.

Brown's cousin, Eric Davis, told the BBC's Aleem Maqbool that the officer must be prosecuted, adding: "The police situation has always been one of distrust and not good for African-Americans."

The authorities are under pressure to release the officer's name, but they say they are worried that his life and that of his family could be in danger.

Four nights of violence have seen heavily armed riot police firing tear gas at demonstrators and looting, arson and the throwing of bottles and Molotov cocktails.

In a specially convened press conference during his holiday, Mr Obama said there was "no excuse" for police to use excessive force against peaceful protesters.

But he also recognised the violence and criminal behaviour police had faced since Mr Brown's killing.

Mr Obama has promised a full investigation by the US Department of Justice into the teenager's death, and the FBI has launched its own inquiry.

(BBC)