Dozens of people were arrested after violence erupted at a protest about a white police officer being found not guilty of murder in the fatal shooting of a black man in the US city of St Louis.

The Missouri city’s police department said that nine officers had been injured and one was taken to hospital after an injury sustained from a thrown brick.

Protesters also broke windows at the house of St Louis’ Mayor Lyda Krewson, and damaged the city’s public library, before riot police dispersed the crowd with tear gas and pepper balls.

“A total of 32 arrests have been made,” the force said in a statement.

“Many of the demonstrators were peaceful, however after dark, many agitators began to destroy property and assault police officers.”

“Orders to disperse were given numerous times”, it said, adding that “tear gas was deployed after officers were assaulted with bricks and bottles”.

However, footage circulating on social media taken from the local Fox 2 news network appeared to show an elderly woman falling to the ground after contact with riot police.

The protests were sparked by Friday’s verdict into the fatal shooting of Anthony Lamar Smith by former St Louis police officer Jason Stockley in December 2011.

In his ruling, Judge Timothy Wilson said the state failed to prove that Mr Stockley did not act in self-defence. The police officer maintained he shot Mr Smith because he believed he was reaching for a handgun, after being pulled over for a suspected drug deal.

State prosecutors claimed Mr Stockley had planted a revolver in Mr Smith’s car after his death to justify the killing, pointing out his DNA was discovered on the weapon, while Mr Smith’s was not.

They also cited internal police vehicle camera footage recorded shortly before the shooting, in which Mr Stockley can be heard saying to his partner, “We’re killing this motherf***er.”

However, Justice Wilson ultimately ruled there was insufficient evidence to support the prosecution’s theory.

After the verdict, St Louis Circuit Attorney Kimberly Gardner, prosecuting, called for a review of the process of pursuing police officers in cases such as Mr Smith’s.

“Officer-involved shootings are very difficult to obtain a guilty verdict,” Ms Gardner told a press conference. “We must re-examine not just how we prosecute these cases, but how we investigate them.”

The National Association for the Advancement of Coloured People (NAACP) has written to President Donald Trump, as well as Attorney General Jeff Sessions, to ask for an urgent review of the case.

“In light of the fact that the community has lost faith in our local authorities to fairly and impartially handle these cases; the immediate engagement of your Justice Department is warranted to provide another set of eyes on this, to get to the truth of what happened and to ensure that justice has been served”, the letter states.