More than 300 children, including two 10-year-olds, were found working at McDonald's restaurants across Kentucky and several other states in violation of federal labor laws, the Labor Department said Tuesday.

In one case, investigators found two 10-year-olds were working unpaid and until as late as 2 a.m. at one McDonald's restaurant in Louisville operated by Bauer Food LLC, which is based in Louisville, the department said in a news release.

The two children prepared and distributed food orders, cleaned the store, worked at the drive-thru window and operated a register, investigators found. One of them was also allowed to operate a deep fryer, a task prohibited for workers under the age of 16 under federal law.

Most of the restaurants, 45 of the 62, were in Kentucky, according to data released by the department.

The two 10-year-olds were among at least 305 children found to have been employed in violation of federal labor laws across 62 McDonald’s locations in Kentucky, Indiana, Maryland and Ohio, operated under three franchisees — Bauer Food LLC, Archways Richwood LLC and Bell Restaurant Group I LLC, the Labor Department said.

Bauer Food LLC said the two 10-year-olds alleged to have been employed at the McDonald’s restaurant were children of a night manager who were visiting their parent at work and were not approved by franchisee organization management to be in that part of the restaurant.

The franchisee said it had since taken steps to ensure policies regarding children visiting a parent or guardian at work were clear to all employees.

"These reports are unacceptable, deeply troubling and run afoul of the high expectations we have for the entire McDonald’s brand," Tiffanie Boyd, senior vice president and chief people officer at McDonald’s USA, said in a statement. "It is not lost on us the significant responsibility we carry to ensure a positive and safe experience for everyone under the Arches."

"I know how important it is that every restaurant fosters a culture of safety. As a mother whose teenage son proudly worked at our local McDonald’s, I feel this on a very personal level," she added. "We are committed to ensuring our franchisees have the resources they need to foster safe workplaces for all employees and maintain compliance with all labor laws."

Archways Richwood LLC did not immediately respond to requests for comment from NBC News early Wednesday. A LinkedIn account appearing to belong to the owner of Bell Restaurant Group I LLC did not immediately respond to a request for comment.

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

The employers face civil money penalties with an estimated combined total of more than $212,000.

Archways Richwood LLC, based in Walton, was found to have allowed 242 children between the ages of 14 and 15 to work beyond allowable hours. Most worked earlier or later in the day than the law permits and more than three hours on school days, the Labor Department said. The employer was expected to be fined an estimated $143,566 in civil money penalties for the violations.

Bell Restaurant Group I LLC, based in Louisville, allowed 39 children between the ages of 14 and 15 to work outside allowable hours, the department said. The employer was expected to face an estimated $29,267 in civil money penalties, the department said.

Bauer Food LLC employed 24 children under the age of 16 to work more than legally permitted hours, according to the department. The employer was expected to be fined an estimated $39,711 in penalties.

Garnett-Civils said the latest incidents came amid an "increase in federal child labor violations, including allowing minors to operate equipment or handle types of work that endangers them or employs them for more hours or later in the day than federal law allows."

While most cases with child labor violations involve minors working longer and later hours than the law permits, the Labor Department found at least 688 minors employed illegally in hazardous occupations in fiscal year 2022, the highest annual count since fiscal year 2011.

Among those was a 15-year-old who was injured while using a deep fryer at a McDonald’s in Morristown, Tennessee, in June 2022, it said.