Seven people were arrested early Sunday morning as police used smoke and tear gas to impose a curfew in a St. Louis suburb where a black teen walking down the street had been shot by a white police officer.
Missouri State Highway Patrol Captain Ron Johnson also said one person was critically wounded after being shot and police are seeking the shooter.
Johnson defended his department's strong strategic response that came after a midnight to 5am curfew took hold in Ferguson, Missouri.
He said the strong police response was precipitated by two events.
People who had broken into a barbecue restaurant and taken position on the roof overlooking approaching police was one strategic concern and another involved a man who flashed a handgun and appeared in the middle of the street as armoured vehicles approached the crowd of protesters.
Johnson said someone also fired at a patrol car, but no officers were injured.
A state of emergency has been declared in suburban St Louis after the US city was hit by another night of violent riots and looting, following the shooting dead of an unarmed black teenager.
Missouri Governor Jay Nixon declared the emergency and imposed a curfew in Ferguson following the week-long series of racially charged protests.
The streets must be emptied starting at midnight for a curfew that will run until 5am until further notice, according to Highway Patrol Captain Ron Johnson, named by the governor to oversee security in the suburb of Ferguson that has been roiled by the August 9 shooting of 18-year-old Michael Brown.
A couple hundred defiant protesters remained in Ferguson after a midnight curfew took effect, while hundreds of other protesters left peacefully before the midnight deadline took effect Sunday morning.
Remaining protesters mingled, chanted and taunted police, some shouting that they would not abide the curfew.
The protesters — chanting ‘‘No justice! No curfew!’’ — refused to leave the area.
As five armoured tactical vehicles approached the crowd, officers spoke through a loudspeaker: ‘‘You are in violation of a state-imposed curfew. You must disperse immediately. Failure to comply may result in arrest.’’
As officers put on gas masks, a chant from the distant crowd emerged: ‘‘We have the right to assemble peacefully.’’
A moment later, police began firing tear gas and smoke into the crowd of protesters.
"The eyes of the world are watching. This is the test of whether a community, this community, any community, can break the cycle of fear, distrust and violence, and replace them with peace, strength and, ultimately, justice," Nixon said in remarks made at a church near Ferguson.
Some in the crowd gathered at the church reacted angrily to the news of a curfew and one interrupted the governor's remarks, shouting that the police officer who killed Brown must be charged with murder to bring peace to the community.
The unrest erupted after Ferguson police officer Darren Wilson, 28, shot and killed Brown last Saturday as Brown and a friend walked down a street that runs through an apartment complex where Brown's grandmother lives.
Tensions have been high all week but escalated on Friday evening (Saturday NZT) as protesters again swarmed through a residential and retail district that has become a virtual war zone, pitting mostly black protesters against mostly white police forces.
On Saturday, people marching through city streets held signs that read "black lives matter," and "Don't shoot."
For days, Brown's family and supporters have demanded the name of the officer, which police repeatedly refused to release. That changed on Friday when Ferguson Police Chief Tom Jackson identified Wilson as the officer involved.
But rather than appease the protesters, Jackson added to the outrage when he announced that Brown had been a suspect in the robbery of a convenience store at the time he was shot, a move that supporters of Brown's family called a "smear" campaign.
The looting started at the same store where Brown was accused of taking cigars, officials said.
Jackson was later forced to acknowledge in a news conference that when Wilson shot Brown, the officer did not know the teen was a suspect in the robbery.
The shooting happened after the officer told Brown and a friend to move out of a street they were walking along when the officer drove by. There was no connection between the shooting and the alleged robbery, Jackson said.
Attorney Ben Crump, who is representing Brown's family, said in a statement issued that the family was "beyond outraged" at the police attempts to "assassinate the character of their son, following such a brutal assassination of his person in broad daylight."
Civil rights activist the Reverand Al Sharpton said he would lead a rally with Brown's family in Ferguson.
"There's nothing more contemptible and offensive to the people of this country than for law enforcement to try to smear a dead man or dead child that can't speak for themselves," Sharpton said at a weekly rally he holds in New York City that is broadcast on the Internet.
Other law enforcement agencies criticized the Ferguson police department for trying to make the alleged robbery an issue connected to the shooting and for releasing a video from inside the store that shows Brown violently shoving a store clerk before he walks out the door.
"We had no involvement whatsoever in releasing that video," said Brian Schellman, a spokesman for the St Louis County Police Department, which is leading the local investigation into the Brown shooting.
Neither the governor's office nor the state highway patrol were involved in the decision either, said Scott Holste, a spokesman for Governor Nixon.
CONFUSION OVER KILLING
The police version of Brown's shooting differs markedly from witness accounts, including that of the friend who was walking with Brown at the time, Dorian Johnson, 22.
In the police version, after Wilson asked Brown to move out of the road onto a sidewalk, Brown reached into the patrol car and struggled with Wilson for the officer's service gun. Wilson, who sustained a facial injury, then shot Brown a number of times.
Johnson and at least one other witness have said that the officer reached out through his car window to grab at Brown and that the teenager was trying to get away from the officer when he was shot.
Brown held up his hands in a sign of surrender but the officer got out of his patrol car and shot Brown several times, they said.
Police have acknowledged that Brown's body was more than 9 metres from the police car when he collapsed and died and that multiple shell casings were found at the scene.
FBI agents were at the scene of the shooting on Saturday interviewing area residents, and civil rights activist Jesse Jackson also visited the site, leading a prayer near a make-shift memorial to Brown just a few feet from where he died.
-Reuters and AP