GREENVILLE, S.C. -- Federal agents said 300 people were arrested on Tuesday during a raid on a chicken processing plant in Greenville as part of an illegal-immigration investigation.

The raid happened at the Columbia Farms plant on Rutherford Road around 9 a.m.

According to U.S. Attorney Walter Wilkins, the raid was part of a 10-month-long investigation into illegal immigrants who work at the plant.

Assistant U.S. Attorney Kevin McDonald said a recent review of immigration paperwork for 825 workers at the plant showed that 775 of them contained false information.

Wilkins said the purpose of Tuesday's raid was to determine the residency status of every person who works at the facility. He said an immigrant who is found to be in the United States illegally will be deported.

"The execution of this search warrant today marks an important phase of this ongoing investigation into the hiring practices of this employer," Wilkins said. "Aggressive enforcement and investigative actions are vital to the integrity of our immigration system."

Wilkins said about 60 of the 300 people arrested have been released because of humanitarian reasons.

Wilkins said before the raid 12 supervisors and managers were charged in the case. They are all accused of falsifying documents to allow illegal immigrants to work at the plant. He said at least seven of them have pleaded guilty to the charges. Two others, Reyes Ramos and Fortino Cruz, have fled and are considered fugitives, Wilkins said.

Agents from the U.S. Immigration and Customs Enforcement executed Tuesday's raid. Kenneth Smith, ICE special agent in charge, said operations like this one are crucial to maintaining the country's immigration system.

"ICE targets employers because the promise of employment draws illegal workers across our borders," Smith said. "By holding employers accountable, we are diminishing the magnet and discouraging others from breaking the law."

Anyone who has family members affected by the raid was asked to call a hotline established by ICE at 866-341-3858.