The police line is several blocks from the lakefront convention center where President Barack Obama is hosting a gathering of world leaders and there is little chance they will be able to reach the meeting.
Some protesters dressed all in black are trying to move east towardMcCormick Place. Some officers are responding by hitting protesters with batons.
The confrontation comes at the end of a march nearly three-hour protest march that was largely peaceful. At the end of the march, several speakers including the Rev. Jesse Jackson asked the protesters to peacefully disperse.