CHICAGO (CBS) -- In a massive show of force, police in riot gear clashed violently with protesters at the end of the anti-NATO summit march on Sunday afternoon.
Police Superintendent Garry McCarthy later said 45 people were arrested.
The clash occurred at 22nd Street and Michigan Avenue--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.
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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.
McCarthy said the 45 arrests Sunday, and 19 before Sunday's big protest event, represented a relatively small number. He said police were showing restraint in the face of hostile protesters, some of whom crossed the line by trying to assault officers.
"This even is going incredibly well," McCarthy told reporters Sunday evening at a news conference.
Four officers suffered minor injuries Sunday, the U.S. Secret Service said. A spokesperson with Mercy Hospital said seven protesters were treated and released.
The Secret Service said two people were detained for attempting to jump a fence near the summit site.
There were many intense moments has 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.
CBS 2's Vince Gerasole reports, there were children in the area. CBS 2's Dave Savini was right in the middle of the standoff as police continued to try to push back the crowd.
During the continued standoff, President Obama's motorcade was leaving McCormick place just a few blocks away.
There were hundreds of police swarming the area, including officers lined up eight-deep in full riot gear. One witness told CBS 2 that some of the officers were laughing at an injured protester.
Similarly, several protesters were taunting the police saying: "You make me sick to my f------ stomach."
The clashes began shortly after 5 p.m. Within an hour, more police were sent and squad rols were arriving to arrest even more people. The crowd was being told to leave to the west and some were complying, but many refused to leave.
By 6:45 p.m. most of the crowd had left the area around 22nd and Michigan where the clashes occurred. A smaller group of protesters remained there, while another group began to march down 24th Street toward McCormick Place where they were met by another line of officers.
Beforehand, several thousand demonstrators peacefully marched downtown into the South Loop, at the foot of McCormick Place where the leaders of the NATO membership are meeting.
McCarthy said protest-related incidents of vandalism had not really materialized during the summit. There were two incidents of damage -- broken windows -- but the superintendent said it wasn't clear if it was related to demonstrators.
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