As anger erupted again on the streets of Ferguson, Missouri, a human rights team from Amnesty International worked on the ground in the US for the first time ever.

Confrontation flared up after an autopsy found that Michael Brown, an unarmed teenager who was fatally shot by an officer on 9 August, had suffered at six bullet wounds including one in the top of his head.

Eye-witnesses report seeing police, with no visible ID badges, hurling tear gas and rubber bullets at protesters and threatening members of the press in another night of demonstrations.

Amnesty International, said it would be observing police and protester activity and gathering testimonies as well as training local activists “on methods of non-violent protest” in an “unprecedented” move by the campaigners.

Unrest in Ferguson over Michael Brown shooting Show all 30 1 /30 Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson A woman, who declined to give her name, joins several hundred others in Oakland, Calif. during a protest against the shooting of Michael Brown, an unarmed black 18-year old by a white police officer in Ferguson, Mo AP Photo/Noah Berger Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Local resident, 9-year-old Ciara Hampton places roses along West Florissant Street as residents called for peaceful demonstrations in Ferguson, Missouri AP Photo/Atlanta Journal-Constitution, Curtis Compton Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Two protesters sit with their faces covered during a peaceful protest takes place on a street in Ferguson, Missouri. Police lowered their profile and refrained from using tear gas, to allow a more orderly night of protests in this St Louis suburb, 10 days after the police shooting of an unarmed black teenager Michael B. Thomas/AFP/Getty Images Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Demonstrators protest the killing of teenager Michael Brown in Ferguson, Missouri Getty Images North America Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Police arrest a demonstrator protesting the killing of teenager Michael Brown in Ferguson, Missouri Photo by Scott Olson/Getty Images Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson People join hands during a protest in Ferguson AP Photo/Charlie Riedel Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Masked protesters pose in the 'Hands up, don't shoot' position: a paraphrase of the alleged last words of Michael Brown before he was shot and killed by a police officer Getty Images Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Demonstrators attend a protest on West Florissant Avenue in Ferguson, Missouri. Police fired tear gas in another night of unrest AFP/Getty Images Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Police fired tear gas in another night of unrest in a Missouri town where a white police officer shot and killed an unarmed black teenager, just hours after President Barack Obama called for calm AFP/Getty Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Police officers tell protesters to move away in another night of protests over the death of teenager Michael Brown AFP/Getty Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Demonstrators attend a protest on West Florissant Avenue in Ferguson, Missouri. Police fired tear gas in another night of unrest AFP/Getty Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson A demonstrator is held by a police officer as he reacts to tear gas thrown to disperse the riots in Ferguson AFP/Getty Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Demonstrators gesture during a protest on West Florissant Avenue in Ferguson, Missouri AFP/Getty Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Law enforcement officers stand guard during a protest on West Florissant Avenue in Ferguson AFP/Getty Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Police officers tell protesters to move away in another night of protests over the death of teenager Michael Brown AFP/Getty Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Demonstrators hold up roses while protesting the fatal police shooting of Michael Brown in Ferguson, Missouri Joe Raedle/Getty Images Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Demonstrators protesting over the police shooting of unarmed black teenager Michael Brown yell at Missouri State Highway Patrol Captain Ronald Johnson (not pictured) in Ferguson, Missouri. Despite the Brown family's continued call for peaceful demonstrations, violent protests have erupted nearly every night in Ferguson since his death Getty Images Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Police officers setup to push protesters to disperse during a protest by using tear gas on West Florissant Road in Ferguson, Missouri. Riot police hurled tear gas and marched on rioters in the St Louis suburb of Ferguson, wracked by race riots since police shot dead an unarmed black teenager AFP/Getty Images Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson A sign left behind after a protest on West Florissant Road in Ferguson, over the shooting of an unarmed black teenager AFP/Getty Images Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson A woman has her face doused with water after being tear gassed by police as she was protesting Michael Brown's death in Ferguson, Missouri Getty Images Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Protestors demonstrate in Ferguson over the police shooting of an unarmed black teenager on 9 August AFP/Getty Images Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Police sit on an armoured vehicle as they hold a line against demonstrators who continue to protest over the shooting of Michael Brown in Ferguson, Missouri PA Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson A protester carries an image of Libra - a symbol of equality - during protests in Ferguson. Riot police hurled tear gas and marched on rioters in the St Louis suburb wracked by race riots since police shot dead an unarmed black teenager on August 9 AFP/Getty Images Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Protestors demonstrate in Ferguson. The Governor of Missouri, Jay Nixon, has criticised police in the town of Ferguson for their 'over-militarised' response to protests following the death last week of Michael Brown, an unarmed black teenager fatally shot by a white officer AFP/Getty Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Protests in Ferguson: Riot police hurled tear gas and marched on rioters in the St Louis suburb wracked by race riots since police shot dead an unarmed black teenager AFP/Getty Images Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson A man protesting Michael Brown's murder walks away from tear gas released by police in Ferguson, Missouri Getty Images Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson People take refuge from tear gas during riots in Ferguson, Missouri, over the death of Michael Brown in Ferguson, Missouri Joshua Lott Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Police officers stand guard during riots in Ferguson, the St Louis suburb wracked by race riots since police shot dead an unarmed black teenager on 9 August AFP/Getty Images Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson A woman has her face doused with water after being tear gassed by police as she was protesting Michael Brown's murder August 17, 2014 in Ferguson, Missouri Getty Images Unrest in Ferguson over Michael Brown shooting Unrest in Ferguson Demonstrators protesting the death of Michael Brown walk past tear gas released by police in Ferguson Getty Images

Amnesty International USA's Executive Director, Steven W Hawkins said that the “people of Ferguson have the right to protest peacefully the lack of accountability for Michael Brown’s shooting”.

Jasmine Heiss, one of the 13-strong team sent by Amnesty, told Buzzfeed that the limits placed on the organisation’s access to post-curfew areas was indicative of “the overall lack of transparency in this investigation”.

“Law enforcement, from the FBI to state and local police, are obligated to respect and uphold the human rights of our communities,” Mr Hawkins said in a statement on 14 August.

“The US cannot continue to allow those obligated and duty-bound to protect to become those who their community fears most," said Amnesty International USA's executive director, Steven W. Hawkins.”

Video: Footage from the streets of Ferguson last night

The fresh dissidence has led to Jay Nixon, the Governor of the state of Missouri, ordering the deployment of National Guard troops to “protect life and property”, he said in a statement this morning.

The military will, he says, will “maintain peace and order” by closing streets and thoroughfares, if it must, after the events that have unfolded have “continued to create conditions of distress and hazard to the safety, welfare and property of the citizens of the community beyond the capacities of local jurisdiction”.

Relations between protesters and police quickly deteriorated yesterday as a second night under curfew began, following the State of Emergency that was declared on Saturday.

Officers say they were responding to gunfire, looting, vandalism and the hurling of Molotov cocktails at them, with at least two people wounded.

"Based on the conditions, I had no alternative but to elevate the level of response," said Captain Ron Johnson, from the Missouri Highway Patrol.

A number of journalists present at the clash in the early hours of this morning reported being threatened with tear gas if they didn’t move, as they were shepherded away from the media enclosure.

Complex Magazine said that police had opened fire into the crowds without warning three hours before the midnight curfew began, causing some children and members of the media to be hit with tear gas and rubber bullets.

Two black journalists from Complex also said that they had been racially profiled, being refused re-entry into the press area whereas white members of the press had been.

While tensions ran high in Missouri, another demonstration in Los Angeles, 1,800 miles away, saw 500 people congregate outside police headquarters to protest the fatal shooting of another unarmed black man, who was killed 11 August.