While I don't disagree with you and I think Newark is a sanctuary city, I just want to clarify what was said in the article. The main ICE offices in NJ are in Newark (select NJ from the drop-down menu), which is the county seat of Essex County.
Enforcement & Removal Operations
Newark Field Office
970 Broad St. 11th Floor
Newark, NJ, 07102
Phone: (973) 645-3666
Area of Responsibility: New Jersey
Email: Newark.Outreach@ice.dhs.gov
Many of the rounded up illegals were operating in Middlesex County, which one can see from the linked map is southwest from Newark.