Minutes later, with federal immigration agents banging on the front door of her apartment in Chicago’s Hermosa neighborhood, she had an answer. Maria’s husband was one of an as-yet-unknown number of people taken into custody Sunday morning in what appeared to be the opening salvo in the long-promised — and much-feared — federal immigration blitz on Chicago.

After a raid at a business in Newark, reportedly without a warrant, here's what to know about ICE and immigration enforcement in America.