The Chicago clerk’s office has kept identifying application materials for more than 2,700 people who used the online CityKey system since December, documents ICE is seeking.

It was a chaotic scene in Chicago's South Loop on Wednesday, as U.S. Immigration and Customs Enforcement agents and other officers took several people into custody.

Immigration advocates and several alderpersons gathered outside the building as the arrests were in progress. They say federal agents detained at least 10 people who had shown up for a routine immigration appointment.