ABC News: Feds: 300 Suspected Illegals Held After S.C. Raid

The raid took place during a shift change. Immigration officials kept the workers inside the House of Raeford's Columbia Farms plant and spent most of the morning trying to interview them and figure out exactly how many are in the U.S. illegally, Assistant U.S. Attorney Kevin McDonald said.

The number could be large. A recent review found that immigration paperwork for more than 775 of 825 workers contained false information, McDonald said.

Immigration agents scoured the plant for paperwork and other information for the investigation.