ST. LOUIS (Reuters) – Activists in St. Louis plan to voice their concerns directly to the mayor on Tuesday over the acquittal of a white policeman who shot a black man to death, a verdict that sparked four night of violent protest.

Mayor Lyda Krewson will speak with residents at a town hall meeting at a local high school, hoping to defuse tensions in a city where demonstrators have clashed with police and destroyed property.

“Let’s show up and hold Mayor Lyda Krewson accountable,” Resist – STL, an activist group, said on Facebook.

The town hall meeting comes four days after a judge found former police officer Jason Stockley, 36, not guilty of first-degree murder in the 2011 killing of Anthony Lamar Smith, 24.

Largely peaceful protests during the day have turned violent at night with some demonstrators carrying guns, bats and hammers, smashing windows, clashing with police and blocking traffic.

Police arrested 123 people on Sunday, when officers in riot gear used pepper spray on activists who defied orders to disperse following larger, peaceful protests. Several hundred people marched again on Monday night in a peaceful demonstration as on-and-off rain appeared to keep some at home.

St. Louis police are investigating whether some of its officers chanted “Whose streets? Our streets,” appropriating a refrain used by the protesters themselves in what one official said could inflame tensions.

A grainy video posted online showed a group of officers and the chant can be heard. A St. Louis Post-Dispatch photographer, David Carson, tweeted that he and others heard officers chant the phrase.

Nicolle Barton, executive director of the St. Louis police civilian oversight board, said: “Certainly we do not want that to be taking place.”

The clashes have evoked memories of riots following the 2014 shooting of a black teenager by a white officer in nearby Ferguson.