Fireworks go off in front of police, who with protesters in front of police headquarters in St. Louis on Monday, June 1, 2020. The small group of protesters was originally part of a much larger group demonstrating earlier in the afternoon against the death of George Floyd. (Colter Peterson/St. Louis Post-Dispatch via AP)

ST. LOUIS (AP) — Police say four officers were hit by gunfire after protests in St. Louis that started peacefully Monday became violent overnight, with demonstrators smashing windows and stealing items from businesses and fires burning in the downtown area.

The police department tweeted early Tuesday that the officers were taken to a hospital with injuries that were not believed to be life-threatening. It was unclear who had fired the shots.

The chaos in St. Louis followed continued protests Monday in Missouri over the death of George Floyd and police treatment of African Americans, with gatherings also held in Kansas City and Jefferson City.

On Monday afternoon, several hundred people rallied peacefully outside the justice center in downtown St. Louis, including Mayor Lyda Krewson and St. Louis Public Safety Director Jimmie Edwards. Protestors later walked to the Gateway Arch National Park and then onto nearby Interstate 64.

But later Monday, protesters gathered in front of police headquarters, where officers fired tear gas. Some protesters smashed windows at a downtown 7-11 store and stole items from inside before the building was set on fire.