St. Louis police said a group of agitators disrupted several downtown St. Louis businesses Sunday evening after a peaceful protest had concluded earlier in the day.

During a press conference early Monday morning, Interim Police Chief Lawrence O'Toole said over 80 people were arrested and at least five weapons were confiscated. On Monday, a press release from the St. Louis Metropolitan Police said they arrested 123 people — most for failure for failure to disperse.

“People setting out to do damage are being arrested, and these criminals we’ve arrested should be held accountable and prosecuted to the fullest extent of the law,” Chief O’Toole said. “We’re in control, this is our city and we are going to protect it.”

PHOTOS | Protests turn destructive as night falls over downtown

Around 8:45 p.m., several reports of broken windows were reported by St. Louis Metropolitan police. Businesses were vandalized at the intersection of Olive and 10th Street and moved toward Washington Avenue. Police soon responded to help contain the crowd of an estimated 100 agitators, forming police lines in order to keep them contained.

Orders were given to the crowd to disperse near the intersection of Tucker Boulevard and Pine Street. Police said the protest was "no longer" peaceful and declared an unlawful assembly.

Related: Our coverage pledge following the Stockley decision

Around 11:30 p.m., police boxed in a group of demonstrators at the intersection of Tucker Boulevard and Pine Street.

One bike officer was transported to an area hospital to be treated for a leg injury. The injury was not classified as life-threatening. Several St. Louis County officers were exposed to unknown chemicals and treated by the St. Louis Fire Department.

According to 5 On Your Side's Christina Coleman, patrons on Sushi Ai on the 900 block of Olive Street were disrupted by an object that shattered the front window of the restaurant. One witness said restaurant staff directed customers into the kitchen to protect them from the incident happening outside.

A separate, peaceful protest was held Sunday afternoon in front of the St. Louis Metropolitan Police Department on the 1900 block of Olive Street. Protest leaders disbanded the group around 7 p.m. While demonstrations have been nonviolent during the day, smaller groups that remain at night have broken windows and thrown objects at police for the past three nights.

WATCH: Mayor Krewson, St. Louis police give an update on Sunday's protests

More protests are expected Monday.

This is a developing story, refresh this story for the latest information.

Related:

- Community comes together to cleanup The Loop

- 'Extremely sad and disappointed': Woman cleaning up on Loop calls for unity

- READ: Entire judgment in Jason Stockley case

- Culpeppers surveillance video released by police

- Peaceful or not: Differing opinions on how protests should be handled

- Small group turns violent in The Loop

- Photos: Protests turn destructive as night falls over downtown