A man is reportedly in a critical condition after being shot during a demonstration in Ferguson, Missouri, as protesters defied a police-imposed curfew.  The man was transferred to hospital and “may lose [his] life”, the Huffington Post reports.  It was not immediately clear whether the injured man was a protestor or not.  Police said that seven people were arrested at the gathering, which came days after police shot dead an unarmed black teen, triggering a wave of rioting.  Missouri Governor Jay Nixon declared a state of emergency and a curfew starting at midnight Saturday local time (3pm AEST) until 5am (8pm AEST) for the St. Louis suburb of Ferguson, where 18-year-old Michael Brown was shot dead by police on August 9.  Ferguson was mostly peaceful when the curfew began on Sunday, local media reported. But a crowd of about 200 protesters gathered in the area where Brown was shot and defied orders to disperse.  Heavily armed riot police, backed up by reinforcements in armored vehicles, hurled smoke canisters and slowly moved in to break up the crowd. While the media images were dramatic, there were no reported incidents of violence.  Mr Nixon said he ordered the measures "to protect the people and property of Ferguson" after looters raided town stores and scuffled with police overnight Friday to Saturday.  Police had earlier used tear gas on protesters. (Getty)  The goal is "to contain those who are drowning out the voice of the people with their actions," said Mr Nixon, speaking at a press conference Saturday held at a local church.  Mr Nixon was repeatedly interrupted by locals angered by an apparent lack of accountability for the largely white police force responsible for Brown's death in the majority black area.  "Excuse me, governor, you need to charge that police officer with murder," said a heckler, referring to the white officer who shot Brown. "Yeah!" cried out supporters.  "Call for an investigation," said another heckler, as palpable anger and frustration simmered in the church hall. "Where's the indictment?"  Others demanded that police guard their homes and businesses.  Missouri Highway Patrol Captain Ron Johnson, the African-American officer that Mr Nixon put in charge of restoring peace, stepped forward to speak.  "Yelling at each other is not going to solve that," Mr Johnson said.  "I don't care who you are, how old you are, and I don't care if you were peaceful protesters last night or a rioter rioting, you'll still get the same answers. Tonight we will enforce it with curfew. We won't enforce it with trucks and tear gas. We'll communicate and tell you... it's time to go home."  Demonstrators taunt police during a protest. (Photo by Scott Olson/Getty Images)  Mr Nixon also said 40 more FBI agents arrived in Ferguson to advance the investigation into Brown's death. Many went door to door in the community seeking additional witnesses.  Riot police fired tear gas and clashed with looters overnight Friday to Saturday, hours after police named Brown as a suspect in the robbery of a Ferguson convenience store.  Gangs of thieves targeted several stores, including the one that Brown allegedly robbed just before he was shot dead on August 9.  Police in riot gear watch protesters in Ferguson, Missouri, after a white police officer fatally shot Michael Brown, an unarmed black teenager, in the St. Louis suburb. (AP Photo/Jeff Roberson)  Protesters also hurled Molotov cocktails and bricks at police, who responded with tear gas, smoke bombs and rubber bullets but they mostly stayed at a distance in armored vehicles and riot gear.  In some cases locals locked arms outside stores to keep looters out, and in others store owners showed up carrying rifles and sidearms to protect their property.  On Saturday afternoon, hundreds of people gathered peacefully near the scene of Brown's shooting, marking the exact moment he was shot a week ago.  Brown's death has renewed a national debate about relations between law enforcement and African Americans.  His family appealed for calm, but accused authorities of a "devious" attempt to smear their son's character after police released surveillance video of the store robbery.  Demonstrators raise their hands during a rally on West Florissant Avenue. (Getty Images)  The video shows a young black man carrying cigars out of a convenience store, and pushing another man who tries to stop him.  The robbery occurred just minutes before the policeman shot Brown dead, but police said the officer stopped the teen for walking in the middle of the street and did not know of the robbery.  A looter breaks into a store in Ferguson, Missouri.(Twitter/@IDAF134)  In Harlem, New York, African American civil rights activist Al Sharpton criticised the video's release, accusing the police of sullying Brown's image in the public eye.  Police face off against rioters. (Twitter/@_KingSoloman_)  "Have we lost our decency when you don't even let people mourn their loved ones without you trying to smear them with things that have nothing to do with the situation?" he asked.  "Are you telling me that you have the right to run down somebody and kill him over three or four cigars?"  Police identified the officer who shot Brown as Darren Wilson, 28, a white, four-year veteran of the force with no disciplinary record.  Separately, Twitter co-founder and St. Louis native Jack Dorsey was in Ferguson over the weekend sending tweets about the protests.  "Feels good to be home. I'll be standing with everyone in Ferguson all weekend #HandsUpDontShoot" the billionaire posted late Friday, before unleashing dozens of Tweets and Vine video posts from protests in the Missouri town.  The hashtag refers to the shooting death of Brown. Some witnesses said the young African American had his hands in the air when he was shot multiple times.  Do you have any news photos or videos?
Vandals have attacked more stores in Ferguson, hours after police said the unarmed black teenager shot dead by a white officer in an incident that unleashed days of rioting was a robbery suspect.