PHOTOS: Powerful Images From Ferguson, Missouri
"What do we want? Justice," the protesters yelled. A state senator said she had tear gas thrown at her.
Demonstrators carried signs as police helicopters circled overhead.
People distributed buttons featuring Brown's picture. "Justice for Michael Brown," the buttons state, featuring silhouettes of raised hands. A witness says Brown's hands were raised when he was fatally shot.
The heavily armed police at times trained weapons on the citizens from an armored truck.
Police, dressed in riot gear, repeatedly warned the protesters to leave.
Police fired smoke bombs soon after, trying to get the crowd to disperse.
Smoke rose on the street.
Protesters returned fire.
The clashes marked the fourth consecutive night of fighting in Ferguson.
One demonstrator tried to kick a smoke grenade back in the direction of police.
Police worked their way down the street, clearing the area of people.
The situation showcases Ferguson's racial divide. Two-thirds of the city's 21,000 residents are black, while all but three of the police force's 53 officers are white.
Ferguson Police Chief Thomas Jackson, who has been the public face of the city torn by Saturday's death of 18-year-old Brown, told reporters Wednesday that his department welcomes Justice Department training on racial relations.
"Unfortunately, an undertow (of racial unrest) has bubbled to the surface," said Jackson. "Race relations is the top priority right now."
Brown was shot multiple times by an officer the police have refused to identify. His body lay slain on the sidewalk for hours as first Ferguson police and then the St. Louis County Police Department processed the scene, drawing immediate criticism aimed at the police for not removing his body more quickly.
Police detained two reporters Wednesday, including the Washington Post's Wesley Lowery, who wrote a first-person account of his arrest.
Antonio French, an Alderman of St. Louis City's 21st Ward, was also arrested, French's wife said. French had spent previous nights posting videos from the streets of Ferguson online, revealing first-hand perspectives into the devastation and suffering.
Missouri Gov. Jay Nixon weighed in, calling for law enforcement to respect the rights of residents and media members.
"Situation in Ferguson does not represent who we are," he wrote.
The St. Louis County investigation of the shooting could take weeks to complete, Jackson said. The FBI is also investigating for potential civil rights violations.
The Associated Press contributed to this report.
Get real-time updates as this story unfolds. To start, just "star" this story in ABC News' phone app. Download ABC News for iPhone here or ABC News for Android here.