Immigration authorities rounded up workers from seven Mississippi food processing plants and in total arrested 680 undocumented individuals.
Family and friends of the individuals waited a plant in Morton, Mississippi on Thursday morning hoping authorities would release them.
By Wednesday night, US Immigration and Customs Enforcement spokesman Bryan Cox told CNN that some of the people detained had been released.
Officials have not specified why some were released.
"Any suggestion that all persons are going to be detained is not correct," Cox said.
Other detainees are still being processed, he said.
Information on the other detainees and when they will be released have yet to be released.