The incident involving Mayor Bob O'Dekirk was caught on video.
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In a video posted on YouTube, the mayor appears to grab a man and throw him to the ground.
In a statement, O'Dekirk, who is a former police officer, said he was "confronted by a rioter then attacked." He is a former police officer and said he used "standard police tactics" to immobilize the man.
Attorneys for the brothers involved said the attack on their clients was unprovoked, and the mayor used excessive force.
"They were not engaging in any type of activity other than protesting," said attorney Michael Baker.