A gas station was looted, and police called for additional units to back up officers already on the street, said Brian Schellman, spokesman with the St. Louis County Police Department.
Video from the scene showed police in riot gear. No injuries were immediately reported.
“They are sending in more officers to try and get the situation under control,” Schellman said.
Ferguson Police Chief Thomas Jackson said that at least 20 police cars were damaged and that the use of tear gas was a high possibility.
“The genesis of this was a physical confrontation,” Jon Belmar, chief of the St. Louis County Police Department, said at a Sunday news conference.
The officer tried to leave his vehicle just before the shooting on Saturday afternoon, but Brown pushed him back into the car, “where he physically assaulted the police officer” and struggled over the officer’s weapon, Belmar said.
A shot was fired inside the police car, and Brown was eventually shot about 35 feet away from the vehicle, Belmar said, adding few details because he didn’t want to “prejudice” the case.
All shell casings collected at the scene were from the officer’s weapon, Belmar said. He further said the medical examiner would issue a ruling on how many times Brown was shot, but “it was more than just a couple.”
The account was in stark contrast to those of witnesses who said Brown did nothing to instigate the shooting and appeared to be surrendering when he was killed.
Ferguson Police cars do not have dash cameras, the department said.
McSpadden was told her son was shot eight times, though witnesses had varying accounts of how many shots were fired. Brown was supposed to start classes at Vatterott College on Monday, she said
Antonio French, the Ward 21 alderman in nearby St. Louis, tweeted numerous photos and videos from the aftermath of the Saturday shooting. Brown was shot shortly after 2 p.m., according to reports.
Hundreds of demonstrators — as many as 1,000 at the height of the protests, according to police — converged on the scene Saturday, at one point driving away a police squad car, French said on Twitter.
Scores of police officers lined the street. One of them held the leash of a barking dog, and French said some officers wielded shotguns. One image showed a riot van on the scene.
Demonstrators held their hands in the air and chanted, “We are Michael Brown.” Others held signs, including one that said, “No justice, no peace” and another that read, “Police stops should not = dead kids.” There were reports that some protesters yelled, “Kill the police.”