ST. PAUL, Minnesota (CNN) -- Police arrested an estimated 200 anti-war protesters Thursday night after using tear gas and percussion grenades to disperse a crowd near the State Capitol, about a mile from the Republican National Convention.
Police used the gas when dozens of marchers -- most in their 20s, some chanting "F--- the police! F--- the police! F--- 'em!" -- tried to cross a bridge leading to the Xcel Center convention site after being warned not to.
Minnesota State Public Safety Commissioner Michael Campion estimates 200 arrests at the interstate overpass near on Marion Street in St. Paul, where police used chemical agents and flash grenades to disperse the crowd.
He said the objective was to contain the protesters and keep them from reaching the convention hall. He says the first night and the last night of the convention were expected to be big for trouble, and they were.
As a line of police clad in riot gear and walking with bicycles approached a woman who refused to get out of their way, several sprayed her with a liquid.
She covered her eyes with one hand and raised two fingers of the other in the shape of a peace sign . 
Watch the protesters march »
A man standing nearby yelled, "I love you! Why are you doing this?" as the woman was shoved to the pavement.
Each time the protesters attempted to cross over the interstate highway separating them from the convention center, police attempted to stop them.
At one point, police on horses, motorcycles and bicycles followed marchers on a street-to-street chase that led through a shopping mall parking lot.
A number of people wound up on the ground with their hands behind heads.
CNN Producer Steve Turnham and Correspondent Joe Johns contributed to this report.
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