Tear gas deployed after St. Louis protest over ex-cop's acquittal turns violent, 32 arrested

— -- Protesters in St. Louis Friday night blocked highways, damaged public and private property, broke windows, threw rocks at the mayor's house and threw bricks at police officers -- who responded by dispersing tear gas -- after a white former police officer earlier in the day was acquitted in the 2011 fatal shooting of a black man.

Thirty-two people were arrested, the St. Louis Metropolitan Police Department said. Ten officers were injured -- 9 St. Louis Police Department officers and one Missouri Highway Patrol officer -- two of whom were transported to a hospital with injuries sustained after being hit by a brick. Some officers were wearing protective gear due to items being thrown at them.

St. Louis Circuit Judge Timothy Wilson found 36-year-old Jason Stockley not guilty of first-degree murder and armed criminal action. On Dec. 20, 2011, the then-police officer shot 24-year-old Lamar Smith five times after a high-speed chase and crash.

Hundreds of people were part of the massive protest, ABC St. Louis affiliate KDNL reported.

At 10:08 p.m. local time, police declared the gathering an "unlawful assembly," tweeting, "those refusing to leave are subject to arrest."

Less than 20 minutes after tweeting that the protest was an unlawful assembly, police announced tear gas had been dispersed, tweeting, "Tear gas was deployed because agitators became violent towards officers and destroyed property at Kingshighway & Waterman #stlverdict."

Police took to Twitter documenting the violent aspect of the protest, including the blocking by protesters of highways and other thoroughfares and other acts of civil disobedience.

"Agitators have converged on Mayor Krewson's house," police tweeted at 9:47 p.m. "Throwing rocks and breaking windows, despite being instructed not to."

A subsequent tweet read, "Agitators refuse to disperse causing property damage near Mayor's home. Those who don't comply w/police orders subject to arrest #stlverdict."

The violence continued past 11 p.m., with police tweeting at 10:29 p.m., "Destruction of public and private property continues in the #CWE neighborhood. We are doing everything we can to keep you safe #stlverdict." Then at 11:30 p.m. police tweeted, "Agitators are being warned that this is no longer a lawful assembly. If they do not disperse, they will be subject to arrest. #stlverdict."

Video from the protests showed demonstrators marching while chanting phrases including “no justice, no peace” and "if you kill our kids, we’ll kill your economy."

Damone Smith, a 52-year-old electrician who was among the motorists re-routed away from the area, told the St. Louis Post-Dispatch that he believed the verdict to be “disgusting.”

“I’m proud of these people protesting,” Smith, who is black, told the Post-Dispatch. “If you look like me, then you feel like there is no other way to express yourself in this kind of verdict. Time and time again, African-American men are killed by police, and nobody is held accountable.”

Officials also tweeted a video of protesters stomping on the hood of a police car.

Some demonstrators were seen openly carrying rifles on the streets, which is legal in Missouri, according to The Associated Press, but there have been no reports of weapons being fired.

Earlier in the evening, police said the protests have been "for the most part" nonviolent, adding "there have been some tense moments where agitators became destructive."

Several companies -- including Wells Fargo, Stifel and Nestle Purina Petcare -- sent thousands of employees home as protests grew Friday morning, the Post-Dispatch reported.

Stockley told the Post-Dispatch on Friday that he “can feel for” and “understand” what Smith’s family is going through. “I know everyone wants someone to blame, but I’m just not the guy,” Stockley told the local newspaper.

Stockley's acquittal also elicited outrage from several local officials, condemning the anxiously awaited bench verdict.

"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,” Missouri state Rep. Michael Butler said in a statement. “And a shot in the heart to the family of the victim,” he said of Smith.

“This system and all the politicians calling for peace are ignoring the pain this verdict causes our communities,” Butler added. “We will be nonviolent but we will not settle on peace. No justice. No peace.”

St. Louis Mayor Lyda Krewson offered a more measured response, though equally emotional.

"My thoughts and prayers are with the family and friends of Anthony Lamar Smith, our police, judge, prosecutor, our citizens who find no comfort or justice, and everyone involved in this difficult case," she said in a statement.

"I am appalled at what happened to Anthony Lamar Smith. I am sobered by this outcome. Frustration, anger, hurt, pain, hope and love all intermingle."

Stockley and his partner at the time, Brian Bianchi, were trying to apprehend Smith for a suspected drug deal at a Church's Chicken restaurant, according to court documents.

Stockley was facing up to life in prison without parole had he been convicted of both charges.

Crowds of people gathered today near the courthouse in downtown St. Louis to protest the ruling. Police blocked streets nearby so demonstrators could march.

Missouri Gov. Eric Greitens, anticipating protests in response to the controversial ruling, released a statement saying he understood the verdict is painful for many St. Louisans.

"We know this verdict causes pain for many people," Greitens said. "I'm committed to protecting everyone's constitutional right to protest peacefully, while also protecting people's lives, homes and communities. For anyone who protests, please do so peacefully."

Stockley's defense attorneys argued that the then-officer acted "reasonably" in self-defense in killing a drug suspect he believed was reaching for a hidden gun.

Prosecutors alleged that Stockley planted a .38-caliber revolver in Smith's Buick after he shot him.

In his verdict, Wilson wrote that the court "is simply not firmly convinced of [Stockley's] guilt."

And because prosecutors "failed to prove beyond a reasonable doubt that [Stockley's] use of deadly force was not justified in self-defense," Wilson wrote that he could not address lesser charges of homicide, including involuntary manslaughter.

ABC News' James Hill and Will Gretsky contributed to this report.