The renewed unrest came hours after police said Michael Brown, 18, had been the suspect in a robbery at a convenience store in the St Louis suburb of Ferguson, minutes before a policeman shot him dead.
Police also named the white officer involved in the shooting in the majority black area, but after a calm Thursday night, the announcements served only to ratchet up tensions again, with people targeting shops, reportedly including the one where Brown carried out the alleged robbery on August 9.
Police -- who have been accused of a heavy-handed response -- retaliated with tear gas, smoke bombs and rubber bullets, but they mostly stayed at a distance in armoured vehicles and riot gear, news reports said.
"If you're getting conflicting reports, it's because there's chaos here. It's dead in some areas, crazy in others.#Ferguson," wrote BuzzFeed reporter Joel Anderson on Twitter.
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Brown's death at the hands of an overwhelmingly white police force has renewed a national debate about relations between law enforcement and African Americans.
"There is nothing based on the facts that have been placed before us that can justify the execution-style murder of their child by this police officer as he held his hands up, which is the universal sign of surrender," a lawyer for the family said.
Ferguson police chief Thomas Jackson identified the officer who shot Brown as Darren Wilson, 28, a white, four-year veteran of the force with no disciplinary record.
Wilson -- in a patrol car -- stopped Brown "because he was walking down the street, stopping traffic. That was it," Jackson said.
Wilson's home in a mostly white town some 30 kilometers from Ferguson has been under police protection, but neighbours told The Washington Post that the officer got "spooked and took off pretty quickly before the name was announced."
Missouri Governor Jay Nixon has drafted in state police to take over from local police and placed Ron Johnson, an African-American officer, in charge.
"Long night. Thanks to all who tried to stop unnecessary violence. I will be in Ferguson today," Nixon said on Twitter on Saturday, as St Louis County police and the FBI continue to conduct parallel investigations into the fatal shooting.