Update 1:59 p.m. Missouri Gov. Jay Nixon declared a state of emergency Saturday and imposed a curfew in the St. Louis suburb where a black teenager was shot to death by a white police officer a week ago.
Nixon said that though many protesters were making themselves heard peacefully, the state would not allow a handful of looters to endanger the community. The curfew will run from midnight to 5 a.m.
"We must first have and maintain peace. This is a test. The eyes of the world are watching," Nixon said. "We cannot allow the ill will of the few to undermine the good will of the many."
Tensions in Ferguson flared late Friday after police released the name of the officer who fatally shot 18-year-old Michael Brown and documents alleging Brown robbed a store before he died.
Nixon also said the U.S. Department of Justice is beefing up its investigation of the shooting.
Missouri State Highway Patrol Capt. Ron Johnson, who is in charge of security in Ferguson, said there were 40 FBI agents going door-to-door starting Saturday, talking to people who might have seen or have information about the shooting.
Nixon and Johnson spoke at a church in Ferguson, where they were interrupted repeatedly by people demanding justice and objecting to the curfew.
Johnson assured those in attendance that police would communicate with protesters and give them ample opportunity to observe the curfew.
"You saw people sitting in the street and they had the chance to get up," he said. "And that's how it's going to continue."
Previously: Police, protesters clash again in Ferguson
Anger spurred by the death of a black teenager at the hands of a white police officer in a St. Louis suburb boiled over again when protesters stormed into a Missouri convenience store — the same one the teen was accused of robbing.
Missouri Gov. Jay Nixon's office tweeted "Long night. Thanks to all who tried to stop unnecessary violence" and said the governor would be in Ferguson, Missouri, on Saturday to meet with local leaders.
Police and about 200 protesters clashed late Friday after another tense day that began with authorities identifying the officer who fatally shot Michael Brown as 28-year-old Darren Wilson. At the same time, Ferguson Police Chief Thomas Jackson released documents alleging Brown, 18, had stolen a $48.99 box of cigars from the convenience store and strong-armed a man on his way out.
Just before midnight, some in what had been a large, rowdy but mostly peaceful crowd broke into that same small store, Ferguson Market & Liquor, and began looting it, Missouri State Highway Patrol Capt. Ron Johnson said. Some protesters yelled at the aggressors to stop what they were doing, and about a dozen eventually helped protect the store.
Teams of police officers holding rifles and dressed in riot gear used their cars to block a one-mile stretch of West Florissant Avenue, the street at the center of the protests. Occasional firecrackers sounded in the distance.
Some in the crowd began throwing rocks and other objects at police, Johnson said. One officer was hurt; details were not immediately available. Johnson said police backed off to try and ease the tension. No arrests were made.
"We had to evaluate the security of the officers there and also the rioters," Johnson said. "We just felt it was better to move back."
Brown's death a week ago had already ignited several days of clashes with furious protesters. Tensions eased Thursday after Nixon turned oversight of the protests over to the Missouri Highway Patrol. Gone were the police in riot gear and armored vehicles, replaced by the new patrol commander who personally walked through the streets with demonstrators. But Friday night marked a resurgence of the unrest.
Local officers faced strong criticism earlier in the week for their use of tear gas and rubber bullets against protesters. Johnson said one tear gas canister was deployed Friday night after the group of rioters became unruly.
Jackson's decision to spell out the allegations that Brown committed the robbery, and his releasing of surveillance video, angered Brown's family and many in the community.
"They have attempted to taint the investigation," U.S. Rep. William Lacy Clay told protesters through a bullhorn Friday night. "They are trying to influence a jury pool by the stunt they pulled today."
Family attorney Daryl Parks acknowledged the man in the footage "appears to be" Brown. But he and others said Brown's family was blindsided by the allegations and release of the footage. They said that even if it was Brown, the crime didn't justify the shooting after Brown put up his hands in surrender, as witnesses describe.
Another family attorney, Benjamin Crump, said police "are choosing to disseminate information that is very strategic to try to help them justify the killing.
Wilson, the officer who shot Brown, did not know the teen was a robbery suspect at the time of the shooting and stopped Brown and a companion "because they were walking down the middle of the street blocking traffic," Jackson said Friday. Police said they found evidence of the stolen merchandise on Brown's body.
Wilson is a six-year police veteran — two in neighboring Jennings and four in Ferguson — and had no previous complaints filed against him, Jackson said, describing him as "a gentle, quiet man" who had been "an excellent officer."
The Ferguson Police Department has refused to say anything about Wilson's whereabouts, and Associated Press reporters were unable to contact him at any addresses or phone numbers listed under that name in the St. Louis area.
Wilson has been on paid administrative leave since the shooting. St. Louis County prosecutor Bob McCulloch said it could be weeks before the investigation wraps up.
St. Louis County Executive Charlie Dooley asked Missouri Attorney General Chris Koster on Friday to take over the case, saying he did not believe McCulloch could be objective. Koster said Missouri law does not allow it unless McCulloch opts out, and McCulloch spokesman Ed Magee said the prosecutor has no plans to surrender the case.
Also Friday, the U.S. Justice Department said that FBI agents had conducted several interviews with witnesses as part of a civil-rights investigation into Brown's death. In the days ahead, the agents planned to canvass the neighborhood for more information, the statement said.
This story has been updated.