In a coordinated sting, more than 600 agents from Immigration and Customs Enforcement showed up at the sites with federal warrants that allowed them to search the premises. About 680 immigrants who were believed to be working without legal documentation were apprehended and taken away on buses.

Lindsay Williams, a spokesman for the agency, said the federal agents executed the search warrants in conjunction with the United States Attorney’s Office for the Southern District of Mississippi. The operation was the culmination of a yearlong investigation, and born of policies put forth by the Trump administration — Mr. Trump has made illegal immigration a trademark issue and  recently vowed to deport millions of undocumented immigrants.