Two 10-year-old children were found working at a McDonald's restaurant in Louisville, USA, sometimes until 2 a.m., the Department of Labor said on Tuesday.

The revelation was part of an investigation into violations of child labor law in the southeastern United States. The agency also found that three franchises that own over 60 McDonald's locations in Kentucky, Indiana, Maryland, and Ohio, "employed 305 children to work more hours than legally allowed and perform tasks prohibited by law for young workers," the Department of Labor said in a statement.

The franchises, Bauer Food, Archways Richwood, and Bell Restaurant Group, did not immediately respond to a request for comment.

"Investigators from the Department's Wage and Hour Division found two 10-year-old workers at a McDonald's restaurant in Louisville among numerous violations of federal labor laws committed by three Kentucky McDonald's franchisees," the statement said. "Investigators also found two 10-year-old children working but not getting paid, and sometimes working until 2 a.m."

The three franchises face combined civil fines of $212,754 for the child labor violations, according to the statement.

"Too often, employers fail to follow child labor laws that protect young workers," said Karen Garnett-Civils, district director of the agency's Wage and Hour Division, in a statement. "Under no circumstances should a 10-year-old be working in a fast-food kitchen around hot grills, ovens, and fryers."