Sept. 15 (UPI) -- Police in St. Louis said protests following the acquittal Friday of former police officer Jason Stockley in the 2011 shooting death of a black motorist are "no longer considered peaceful" and are asking people to avoid the city's downtown area.
The Metropolitan Police Department reported at least 13 protesters were arrested and four police officers injured, although police said the protests were mostly non-violent.
Several hundred people gathered in downtown St. Louis early Friday afternoon after the verdict, with some groups moving toward police headquarters and others blocking parts of other streets in the city.
"For the most part, the demonstrations have been peaceful," MPD posted on Twitter. "There have been some tense moments where agitators became destructive."
Stockley was acquitted of murder charges tied to the 2011 shooting death of 24-year-old Anthony Lamar Smith, which followed a police chase allegedly tied to a drug deal.
"This not-guilty verdict of a police officer who violently killed a citizen is another slap in the face to the black community in St. Louis -- and a shot in the heart to the family of the victim," Missouri state Rep. Michael Butler said in a statement.
"This system and all the politicians calling for peace are ignoring the pain this verdict causes our communities. We will be non-violent but we will not settle on peace. No justice. No peace."
The city -- police and schools, among others -- braced itself for protests after the the verdict was announced.
Since the verdict, police report that most protesters were peaceful, but point out that those throwing bottles and rocks at police, jumping on police cars, and otherwise assaulting officers would be arrested. Several protesters were maced after throwing bottles at police, MPD said.