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.

The number of arrests there was uncertain. Illinois officials, including the governor, said they had not been given advance notice.

Immigration and Customs Enforcement, along with several other federal agencies, began what they called "enhanced targeted operations" on Sunday in Chicago.