Police Superintendent Garry McCarthy later said more than 40 people were arrested and at least four officers were taken to the hospital with minor injuries.
The clash occurred a few blocks away from where President Obama and other world leaders were meeting for the NATO summit–as the protesters tried to leave the rally at the end of a huge anti-NATO march.
McCarthy was seen right in the middle of the fray, directing his officers.
Police were yelling at the crowd to move back as some of the protesters tried to rupture the line and threw objects at officers. The objects bounced off police officers, who wore riot-control gear, including protective visors. Several people could be seen being taken into custody.
Several officers were reportedly injured at the melee near McCormick Place. Meanwhile, people allied with the Occupy Chicago movement were saying several demonstrators were injured.
There were many intense moments as protesters clad in black began shoving. Police responded by striking them with clubs.
At one point, officers were putting on gas masks after seeing somebody trying to open a canister. Protesters were also seen wearing masks and forming human chains by joining arms.
“We responded, so far today we are up to 45 arrests today, I cannot tell you how many happened here today I’m sorry, I don’t have it all together yet,” said Garry McCarthy, Chicago Police Superintendent
“We have at least four officers who went to the hospital none too seriously, bumps and bruises, one officers was stabbed in the leg.”