SIOUX FALLS, S.D. (KELO) — The U.S. Department of Labor is asking a federal court to issue an injunction against Packers Sanitation Services to stop illegally employing minors.

The filing comes after an investigation by the department found that Packers employed at least 31 children between the ages of 13 and 17 at JBS in Grand Island, Nebraska and Worthington, Minnestoa as well as at Turkey Valley Farms in Marshall, Minnesota.

The children were working hazardous jobs that included operating dangerous powered equipment during overnight shifts. The investigation found that some of the children suffered chemical burns and other injuries.

The sanitation service also allegedly deleted or manipulated employee files and used intimidation to stop the minors from cooperating in the investigation.

Packers Sanitation Services offers services in close to 700 food processing facilities across the country and employs 17,000 workers.