Police have shot dead a knife-wielding man near the US town hit by 10 days of protests over the police killing of an unarmed black teenager, threatening to further ratchet up tensions.
Tuesday's shooting came as the lawyer for the family of Michael Brown, who was shot dead by police in Ferguson on August 9, said that the 18-year-old college student's funeral would be held on Monday.
Civic leaders in Ferguson, in Missouri, had called for "night-time quiet and reconciliation" after another night of protests and violence in the majority black town.
But, a short drive away in St. Louis proper, police - who have been criticised for an aggressive response to the demonstrations - faced yet more scrutiny when they shot dead an apparently agitated man armed with a knife who yelled "kill me now" and approached a patrol.
The world's media descended on the street, dozens of reporters having been in nearby Ferguson covering the ongoing unrest that has cast an unfavourable light on the United States' racial divide, as well as law-enforcement tactics.
Onlookers gathered at the yellow incident tape sealing off the scene of Tuesday's shooting outside a convenience store, some of them chanting the slogan of the protests: "Hands up, don't shoot."
Captain Ed Kuntz told reporters at the scene that an investigation had been launched, but, based on what he had heard, "it seems reasonable to say it was justifiable."
"Whenever there's a police shooting, tensions are always more high," he admitted, while insisting: "Right now we are focused on preserving life and protecting property."
Overnight in Ferguson, protesters shot at police and threw rocks and firebombs in a new spasm of violence that left six wounded and led to 31 arrests.
Police responded with tear gas to disperse the crowd of about 200 in the town, Captain Ron Johnson of the Missouri Highway Patrol said.
Michael Brown was killed in broad daylight on a residential street by Darren Wilson, a 28-year-old white police officer - triggering a wave of community protests.
Although police have since fingered Brown as a robbery suspect, he was unarmed at the time of shooting and some witnesses have said he was surrendering when he was hit six times, twice in head.
"Funeral arrangements for #MichaelBrown have been confirmed for Monday. A press release with complete details will follow," Benjamin Crump, the family's lawyer, tweeted.
The message was retweeted nearly 300 times in less than hour, reflecting the intense interest in the fatal shooting, which has stirred racial tensions, although there have been only limited protests in other parts of the US.
US National Guard troops have been deployed to Ferguson to help get a grip on the unrest, amid criticism of the distrusted local force's handling of the protests, with even
President Barack Obama saying there was no excuse for local police to use "excessive force."
He urged Missouri to make only "limited" use of the National Guard, which is operating under police supervision.
Ferguson residents accuse the mostly white police force of frequent abuses.