Media playback is unsupported on your device Media caption Aleem Maqbool: "To some of them, the police look like an invading army"

The US state of Missouri is sending the National Guard to the town of Ferguson as protests escalate over the police shooting of an unarmed black teenager.

Governor Jay Nixon signed an order to "help restore peace and order".

An independent autopsy has found Michael Brown, 18, was shot by a Ferguson police officer six times, including twice in the head.

On Sunday evening police dispersed angry crowds shortly before a second consecutive night under curfew began.

The mother of Michael Brown has called for the arrest of the officer who killed her son on 9 August. He has been suspended pending a full investigation.

Media playback is unsupported on your device Media caption Michael Brown's mother Lesley: "Make this man accountable for his actions"

Officials last week confirmed that Darren Wilson, a six-year police veteran with no previous complaints against him, has been on paid administrative leave since the shooting.

In an interview with US media, Mr Brown's mother said the only way to restore peace in Ferguson was by "arresting [Mr Wilson] and making him accountable for his actions".

A preliminary post-mortem examination by the St Louis County Medical Examiner's office on the day after Mr Brown's death found he had been shot, police said, without disclosing how many times.

But a preliminary private post-mortem report has since revealed that he was shot at least six times, including twice in the head, the New York Times reports.

The probable fatal shot entered the top of Mr Brown's head, forensic pathologist Michael Baden was quoted by the paper as saying.

What is the National Guard?

Image copyright National Guard

Reserve group organised by the US Army and US Air Force.

Every US state and territory has a National Guard.

Can be called on by state governors during emergencies including riots and natural disasters.

Guard units may also be ordered into active duty for up to two years by the US president during national emergency.

Enlistment is voluntary

Missouri National Guard

Gunpowder residue suggested he was not shot at close range, but that finding could change once Mr Baden has access to the clothes Mr Brown was wearing at the time of his death, the newspaper reported.

He flew to Missouri on Sunday to conduct a separate autopsy at the request of the family.

After dark on Sunday, police in Ferguson, a suburb of St Louis, said they came under attack and had no alternative but to respond.

Image copyright Getty Images Image caption Protesters ignored Sunday's curfew and marched down the city's main streets

Image copyright Reuters Image caption Residents gathered in protest during the day on Sunday

Image copyright Reuters Image caption Security forces accused some of the demonstrators of advancing on a police command post

Capt Ron Johnson said protesters had shot at officers and thrown petrol bombs and bottles before the five-hour curfew started at midnight local time (05:00 GMT).

He described the violence as "premeditated criminal acts" intended to provoke a reaction. A number of people were injured during the unrest, and police made several arrests.

No major incidents were reported during the curfew, which has now ended.

Missouri declared a state of emergency and imposed a curfew on Saturday in response to the escalating violence.

'Disservice to community'

The killing of Mr Brown by a white policeman in a street has inflamed racial tensions in the largely black suburb.

Officer Darren Wilson shot the teenager after reportedly stopping him for walking in the street.

Image copyright Getty Images Image caption Tensions between the demonstrators and police quickly escalated

Image copyright Reuters Image caption This women had water poured over her face to help counter the effects of tear gas

Image copyright Getty Images Image caption "Hands up, Don't Shoot" has become a key slogan in the protests

The governor of Missouri has criticised police for releasing CCTV footage which apparently shows Mr Brown stealing cigars from a local shop some hours before his death.

Mr Nixon said the release of the footage "appeared to cast aspersions" on the dead man, saying "it made emotions raw".

But he also condemned the protesters: "These violent acts are a disservice to the family of Michael Brown and his memory and to the people of this community who yearn for justice to be served and to feel safe in their own homes."

Ferguson unrest 21,205 Population of Ferguson, Missouri 65% Black or black African 6% Police officers are black

9% Unemployed

21% Families living below the poverty line Getty

In Pictures: Clashes in Ferguson

Timeline of events

Image copyright Other - Facebook Image caption Michael Brown had recently graduated from high school.