OMAHA, Neb. — The Latest on a large federal immigration operation targeting businesses in Nebraska and Minnesota that officials say knowingly hired and mistreated immigrants who are in the U.S. illegally (all times local):

5:15 p.m.

Federal officials say a large investigation into businesses believed to be involved in a scheme to knowingly hire immigrant laborers in the U.S. illegally saw search warrants served on several businesses in Nebraska and Minnesota.

Those businesses included several in O'Neill, Nebraska, a town of about 3,000 about 160 miles northwest of Omaha.

Investigators say warrants were served Wednesday at Elkhorn River Farms, hydroponic tomato grower O'Neill Ventures, La Herradura restaurant and grocery store El Mercadito, all in O'Neill.

Calls to those businesses Wednesday went unanswered or messages left were not returned.

In Minnesota, pork producing giant Christensen Farms saw search warrants served at its headquarters in Sleepy Eye, Minnesota, as well as its truck wash facility in Appleton, Minnesota and a producer plant in Atkinson, Nebraska.

Christensen Farms spokeswoman Amber Portner said her company is cooperating with agents. She said she knew of no arrests at any of the company's locations Wednesday.

Other businesses were in Stromsburg, Ainsworth, Bartlett and Royal, all in Nebraska.

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4:20 p.m.

Federal officials say a series of arrest warrants have been executed for 17 people charging them with fraud and money laundering in Nebraska and Minnesota in connection with a scheme to exploit immigrant workers who were in the country illegally.

Officials with U.S. Immigration and Customs Enforcement's investigative arm, Homeland Security Investigations, say 14 of those people are in custody, and three others are being sought.

More than 130 workers were also arrested as officials served search warrants at agricultural businesses in Nebraska and Minnesota.

Officials also searched for documents at several places in Nebraska and at pork producer Christensen Farms in Sleepy Eye, Minnesota; Appleton, Minnesota; and Ainsworth, Nebraska. A home in Las Vegas also was searched.