(CBS) – Demonstrators staged two different marches Monday in the latest round of Chicago protests to denounce officer-involved shootings of black individuals.

One group – organized by two teen girls — staged a sit-in at Millennium Park that turned into a march. They headed to the other side of the Loop, where additional hundreds gathered at Federal Plaza.

The combined group of marchers, estimated to be more than 1,000 strong, proceeded to march into the evening, at times stopping traffic by blocking intersections.

Chicago police officers, including cops on bicycles,  monitored the protesters and followed their march.

Eventually, the demonstration ended up back at Millennium Park. Chicago activists say they specifically want the city to create an elected Civilian Police Accountability Council.

They also said police have to be more respectful of African-Americans and the Justice Department should punish police officers who shoot people.

The demonstrations began last week, in the wake of police-involved shootings in suburban Minneapolis and Baton Rouge, La. The protests in Chicago have been relatively peaceful, though police scuffled with some demonstrators Saturday night near the Taste of Chicago.

Nearly two dozen demonstrators were arrested over the weekend.

Earlier Monday, Chicago Mayor Rahm Emanuel praised the way officers handled protests over the weekend.