NEW : Police arrested Tom Barrett , Saturday , in connection with the attack . Police : Man beat Mayor Barrett with metal pipe at state fair on 20 . Anthony Peters heard a woman screaming and tried to help her , dialing 911 . Man who had been beating the woman then started hitting Barrett , police say .
NEW : Police arrested Anthony Peters , 20 , in connection with the attack . Police : Man beat Mayor Tom Barrett with metal pipe at state fair on Saturday . Barrett heard a woman screaming and tried to help her , dialing 911 . Man who had been beating the woman then started hitting Barrett , police say .