Tensions have risen again with one person shot in the Milwaukee neighbourhood where the fatal shooting of a suspect by a police officer set off rioting and arson the previous night and prompted Wisconsin's governor to activate the National Guard.
After small groups of demonstrators gathered earlier in peaceful vigils, Milwaukee police said late on Sunday night they began attempting to disperse crowds after shots were fired and objects were thrown by some protesters.
Police said they rescued one shooting victim, who was rushed to hospital. It was not known whether the person was a protester, officer, or bystander.
About 20 police in riot gear faced a group of more than 100 protesters in the tense standoff.
Police violence against African-Americans has set off intermittent, sometimes violent protests in the past two years, igniting a national race and policing debate in the United States, giving rise to the Black Lives Matter movement.
Wisconsin Governor Scott Walker took the precautionary step in case more violence broke out over the death of Sylville Smith, 23, who was shot while trying to flee from an officer who had stopped his car on Saturday.
Aiming to reassure the community that the police acted properly, Chief Edward Flynn said footage from the officer's body camera showed Smith had turned toward him with a gun in his hand after a traffic stop.
The Sherman Park neighbourhood, where a heated confrontation between residents and officers clad in riot gear turned violent overnight, was peaceful as the sun set.
About 200 people lit candles and gathered around the spot where Smith was shot.
"We are not ignorant and stupid people," a pastor told the crowd, echoing a feeling among many of the city's African-Americans that they are systematically mistreated.
"Every single person needs to be looked upon as human beings and not like savages and animals."
The previous night, gunshots were fired, six businesses were destroyed by fire and police cars damaged before calm was restored in the area, which has a reputation for poverty and crime. Seventeen people were arrested, and four police officers were treated for injuries.
At a news conference with Mayor Tom Barrett, Flynn said the officer who fired the fatal shot was black and media reports also identified Smith as black.
He said a silent video of the incident appeared to show the officer acting within lawful bounds in shooting Smith.
He said the moment when the officer fired his weapon could not be determined because the audio was delayed.
"I'm looking at a silent movie that doesn't necessarily tell me everything that will come out in a thorough investigation," Flynn said. "You know the fog of war. You know first reports are frequently wrong or slightly off.
"I know what I saw. Based on what I saw, didn't hear, don't know what the autopsy results are going to be, he certainly appeared to be within lawful bounds," Flynn said of the officer.
The mayor told the news conference that Smith did not drop the gun as ordered before he was shot.
Smith had a lengthy arrest record, Barrett said, and officials said earlier he was carrying a stolen handgun loaded with 23 rounds of ammunition when stopped for unspecified "suspicious activity."
On Sunday evening, several of Smith's sisters addressed the crowd, saying their brother "did not deserve" to be shot.