Chicago Mayor Rahm Emanuel has angered a local union after police arrested nurses among other Occupy Chicago protesters in enforcement of a local ordinance.

Police arrested 130 people at Grant Park in Chicago, including two nurses, for staying in the park over an hour after the park closed for the night at 11 pm, per the city ordinance. The arrests precipitated “more than a few dozen” nurses to protest inside City Hall at the doors of Emanuel’s office, according to local CBS reporter Susanna Song.